Re: [fpc-pascal] Persistent blocks in Lazarus
[cross-posted to lazarus list = please join there to continue the topic] I am trying to figure out how they work - Block is kept, if cursor moves away. (obvious) - Shift Cursur keys: - Block is extended if cursor was next to block - New block is started , if cursor was away from block. (could also be used to extend the block, like shift-left-mouse) - Block is kept, position/size adjusted if text is typed before, or into the block (exception, column mode block is not adapted) - ctrl-c copies the block, at any time annoyances I found in turbo explorer (the free delphi), not sure if they are supposed to be. - Move the caret via mouse (left click) = block is undone - paste/ctrl-v : the newly inserted text is selected as new block? (this means the current block is lost) That's all the knowledge I have about them sofar. Anyone wants to update me? Martin Andreas Berger wrote: On Thu, Jul 16, 2009 at 01:36:15PM +0200, Andreas Berger wrote: Out of curiosity (because I never used this feature in any editor), what would you use it for? Persistent blocks and the full Wordstar keyboard shortcuts is why I use the Delphi IDE until today. If you miss wordstar stuff, please list it. Well, maybe I should use the Lazarus IDE again for a bit a jot down what I would like. I may even soon have time to help add some options. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Clipboard tutorial.
If you use Lazarus (or at least the LCL) it has a unit Clipbrd and you can do Clipboard.AsText:= FText; Martin Torsten Bonde Christiansen wrote: Graeme Geldenhuys wrote: Torsten Bonde Christiansen wrote: Does anyone know of a page that has a short introduction/tutorial, preferably something that will work cross-platform wise. What GUI toolkit are you using and what platform? Or is it a console based application, which normally means the clipboard only functions inside your own application. GUI application and preferably every possible combination. I'm creating a cross-platform application that in some part of the program should be able to access the clipboard and read data as text only. But from your answer if guess there is no single (simple) way to do this? Regards, Torsten. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Persistent blocks in Lazarus
We are still on the wrong mailing list. Should be laza...@lists.lazarus.freepascal.org Anyway, if it's about SynEdit, feel free to ask where to start looking, I am glad to give some pointers. (But please make sure you are on SVN 0.9.27, since it is completely different) From What I understand, there are 2 issues: - the missing persistent block I don't even know how many persistent-block related commands there are. IIRC from never mind hom many years ago, you have to Key-Shortcuts, to set it's end and begin? (Instead of using shift-cursor?) What other commands are there? It may be possible to break it down into the most needed (set-begin, set-end, copy, move) commands, and otheres that can be added over time? - The Keyboard layout/scheme for wordstar ? How different is that from current default, or classic-scheme default? Martin Andreas Berger wrote: On Thu, Jul 16, 2009 at 01:36:15PM +0200, Andreas Berger wrote: Out of curiosity (because I never used this feature in any editor), what would you use it for? Persistent blocks and the full Wordstar keyboard shortcuts is why I use the Delphi IDE until today. If you miss wordstar stuff, please list it. Well, maybe I should use the Lazarus IDE again for a bit a jot down what I would like. I may even soon have time to help add some options. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Persistent blocks in Lazarus
First of all, Lazarus has it's own mailing list, where you will be more likely to receive answers... Jürgen Hestermann wrote: A question: Do persistent blocks exist the Lazarus editor? Not at current. If it does not exist, is it planned to add? Maybe some day. There is no concrete plan that I know of, so it isn't likely to be any time soon. Patches are welcome. I miss this mode very much. It allowed a way of working which cannot be achieved with the current temporary block mode. Out of curiosity (because I never used this feature in any editor), what would you use it for? Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
implicit exception frames? [Re: [fpc-pascal] If an Assert fails in constructor, then destructor called (?)]
Inoussa OUEDRAOGO wrote:
2009/6/29 Tom Verhoeff t.verho...@tue.nl:
While tracing a nasty bug (?), I discovered the hard way that when
an Assert is done in a constructor, and it fails, then the destructor
(Destroy) is automatically called.
Indeed, when an exception is raised in the constructor, be it an
assert exception or not, the destructor is called to allow the
developer to clean up the in-construction instance's members he has
already initialized.
I just cam across this thread. While I am not opposing the behaviour as
it's stand (it could be useful anyway), it raises another question.
Does that mean that an implicit exception-frame (or whatever this is
called) is inserted *each* time you create/instantiate an object?
Now I understand, object instantiation comes at a cost anyway (memory
allocation), this does add to the cost of instantiation. And the only
error/exception, which really *all* classes can encounter in a
constructor, is out of memory for the object itself = In which case
create is never called (because NewInstance fails), and Destroy should
not be called (as there is no instance that could be passed to destroy).
So There could be calls to create where a developer does not want (and
not need) any exception stack frame.
I also wonder why this special kind of garbage collector? Pascal has
automatic behaviour to handle/free resources for:
- strings
- open array
- apparently classes/objects, but only inside the constructor ?
The last one does of course not apply to objects hold by the failed
object, but I assume that, if Destroy is called, the instance is also freed?
So why are objects handled special in the constructor? If they raise an
exception anywhere else in there live, then you need to care yourself
about catching it, and freeing them?
Anyway, as I said it's not necessarily bad behaviour. but given that
exception handling may add to runtime cost, is there a way to switch
this off?
Like
{$AutoDestroty off}
try
foo := TFoo.create;
except
if foo nil then foo.free;
end;
Martin
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Re: implicit exception frames? [Re: [fpc-pascal] If an Assert fails in constructor, then destructor called (?)]
Michael Van Canneyt wrote: On Thu, 2 Jul 2009, Martin Friebe wrote: Inoussa OUEDRAOGO wrote: Indeed, when an exception is raised in the constructor, be it an assert exception or not, the destructor is called to allow the developer to clean up the in-construction instance's members he has already initialized. I just cam across this thread. While I am not opposing the behaviour as it's stand (it could be useful anyway), it raises another question. Does that mean that an implicit exception-frame (or whatever this is called) is inserted *each* time you create/instantiate an object? Now I understand, object instantiation comes at a cost anyway (memory allocation), this does add to the cost of instantiation. And the only error/exception, which really *all* classes can encounter in a constructor, is out of memory for the object itself = In which case create is never called (because NewInstance fails), and Destroy should not be called (as there is no instance that could be passed to destroy). So There could be calls to create where a developer does not want (and not need) any exception stack frame. I also wonder why this special kind of garbage collector? Pascal has automatic behaviour to handle/free resources for: - strings - open array - apparently classes/objects, but only inside the constructor ? The last one does of course not apply to objects hold by the failed object, but I assume that, if Destroy is called, the instance is also freed? So why are objects handled special in the constructor? If they raise an exception anywhere else in there live, then you need to care yourself about catching it, and freeing them? Because you cannot handle it yourself. Assume the following statement: MyClass:=TSomeClass.Create; if an exception happens inside the constructor, then no instance pointer is assigned to MyClass, since execution after the exception is raised is continued at the next except/finally block. That means you cannot handle destruction in the except block (assuming you wrote one) since you have no pointer to work with. Therefor the constructor code must call the destructor in case of an error. Yes, of course, you are right. It is impossible to handle it in the calling code. As the order is: - instantiation (NewInstance) - Create - exception - assignment to local var = never executed But you can handle it yourself inside the constructor. No one stops the developper from wrtiting Constructor TFoo.Create; begin try ... except self.Destroy; // Or Free ? end; end; - If an error/exception (out of mem) happens in NewInstance, neither Create nor Destroy are called (and neither can they be called, because they need an (empty) instance and there is none) - If an error in Create happens, self is assigned (inside Create). So it can be acted on. Even if, in the above example, this Create was called by a child-class via inherited Create. There is no worry (not even if self.Free is used), that the inherited constructor will find an invalid pointer in self (because/if it has been freed). The code above, never returns to the inherited constructor, unless this inherited constructor itself catches the exception too (in which case it must check ; It would need to be flagged on the exception object) Anyway, while possible, it would be far to complicated. So I agree, the automated handling, ensuring the instance is Destroyed and freed once only, is probably the best Leaves question 2: Is there a way to switch it off, to avoid the cost of creating an exception frame? (if you are either sure your constructor does not throw an exception, or for some reason do not care)? Thanks for the explanation so far Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: implicit exception frames? [Re: [fpc-pascal] If an Assert fails in constructor, then destructor called (?)]
Jonas Maebe wrote: On 02 Jul 2009, at 16:58, Martin Friebe wrote: Leaves question 2: Is there a way to switch it off, to avoid the cost of creating an exception frame? (if you are either sure your constructor does not throw an exception, or for some reason do not care)? http://www.freepascal.org/docs-html/prog/progsu32.html It also applies to the exception frames in constructors. thanks a lot Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Writeable typed constants - what's the point?
Jürgen Hestermann wrote: Paul Nicholls schrieb: I also find writable constants hand for things like this where I can define the 'variable' + values too so I don't have to set the values at run time: But can't you do the same with a variable declaration? If you want to change the value at runtime it's definitely not a constant anymore. Not always Beeing able to change a typed constant was added by Borland as a quick hack (because constants were put into the global data segement even in function declarations) but actually its semantic is wrong. If you can change it, it has to be a variable declaration and you should not be able to change a constant. there is an important difference between const a: word = 1; const a = word(1); // never writeable var a: word = 1; The1 1st and 3rd are (afaik) the same, if used top level, that is in the global context of interface, or implementation . But if procedure Foo; const a: word = 1; var a: word = 1; begin end; Then they are 2 difference things. The var version, acts as if your first statement in the procedure was a:= 1;. It initializes the variable each time you enter the function. If you enter the function recursively, then each level, has it's own a, not touching the value of the callers a The const version act like a global variable. It is set to 1 once at some time before the 1st call to Foo. It will not be initialized again. If Foo chages it, it will keep the changed value, even between calls to Foo. If Foo enters recursively, it act like a global var, there is only one a, shared by all calls to Foo. If Foo is a Method on an object, then it is shared between all instances of the object. The only difference to a global var is, that no one outside Foo can see or access it. And you can't do that with an initialized var. And there are plenty of use-cases for it. Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Writeable typed constants - what's the point?
Graeme Geldenhuys wrote: FPC often implements something that breaks existing code. Examples :)? Please note that I am not saying I disagree with the changes. I know they were introduced for the better. What I am saying, is that changes do get introduced into FPC (for whatever reason) and does sometimes break existing code. Example #1: You cannot pass a property as var parameter anymore. Introduced in v2.2.0 Example #2: Boolean type change in Xlib units. TBool(false) or TBool(true) type usage. Example #3: ComponentState change. I wasn't allowed to use the following code anymore: Include(ComponentState, csDesigning); I think there was a few more that affected fpGUI Toolkit project, but I think you get the idea. As long as code is being maintained, such changes are not the end of the world. :-) But my point is, they do happen! Afaik 1 3 are the same? And if I understand the changes where mad, because this feature was broken before: That is the syntax you mentioned lead to an unpredictable result, and the circumstances under which it did what you wanted could change outside your code and without the intend to make them change. Or in other words: This only worked if a property directly read a variable, but not if it was a function result = meaning you had 2 different types of properties. But only one was documented. Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Generic a Clone method
Torsten Bonde Christiansen wrote: Hi. I was wondering if it is posible to make this type of construct for creating a generic Clone method: (I put it in pastebin): http://pastebin.com/fb495ed7 Explained in words - I'm trying to make a clone method that should be able to copy the content of private variables to a destination object. Naturally this destination would have to be of the same class as the original, but is it posible to determine the size of used space in each derived class, simply by using Sizeof(...). Or do I need to create a seperate clone method for each individual derived class. If it is posible, what memory copy function should I use? There is Object.InstanceSize, which sounds as if it may be what you are looking for. But you have a bigger problem than that. If any member (object variable) is of a ref-counted type (that is strings and dynamic arrays), then any memory copy will mess up. Because in the objects memory, there only are the pointers to the data of strings, and dyn-arrays. If you copy those pointer by hand, then the reference-counts in the actual string or dyn-array are not updated. this leads to at least 2 problems. 1) If the original object was the only holder (or last remaining) of a reference to this string, and your original or new object is destroyed, the ref-count goes down to zero = the string is freed, and the other object points to unallocated memory, or meory allocated to some new/other data) = crash 2) Again if, your old object was the only holder, then the ref-count is still 1. Strings are copy on modify, = 2 copies of a string share memory until one is changed (in which case a copy is made). The need for making the copy is determined by ref-count 1. Your ref-count is 1 = no copy is made, the new object is updating the strings of the old object too Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Generic a Clone method
Torsten Bonde Christiansen wrote: Martin Friebe wrote: If any member (object variable) is of a ref-counted type (that is strings and dynamic arrays), then any memory copy will mess up. Because in the objects memory, there only are the pointers to the data of strings, and dyn-arrays. If you copy those pointer by hand, then the reference-counts in the actual string or dyn-array are not updated. this leads to at least 2 problems. 1) If the original object was the only holder (or last remaining) of a reference to this string, and your original or new object is destroyed, the ref-count goes down to zero = the string is freed, and the other object points to unallocated memory, or meory allocated to some new/other data) = crash 2) Again if, your old object was the only holder, then the ref-count is still 1. Strings are copy on modify, = 2 copies of a string share memory until one is changed (in which case a copy is made). The need for making the copy is determined by ref-count 1. Can this be avoided by using the UniqueString(..) method? If you know where the strings are...; but then it's no longer unique. You can try something else, but i have no idea where it leads too, or if its usable (in objpas mode) type TFoo = object private public end; Acts like a record, with methods, kind of. anyway var a, b: TFoo a:=b; Takes care of everything. BUT those objects are like records. they do not allocate ne meory, each time you create them, they alloc mem when you *declare* them if you pass them to a function in the arg list, they get copied. ( with class the pointer gets copied, because class is in reality a pointer. So you could declare TRealFoo = ^TFoo; then write your constructor to return the pointer, every access would need the dereference of course = massive change to syntax. and so on. If it is for you, you have to RT(F)M yourself Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] A complex trouble(at least for me)
Arí Ricardo Ody wrote: Suppose the following structure: 01 a-1. 03 b-1 pic xxx. 03 b-2 pic 999. 03 b-3. 05 c-1 pic aaa. 05 c-2. 07 d-1 pic zzz. 07 d-2 pic xxx. 05 c-3 pic 99. 03 b-4 pic zzz. 03 b-5. 05 e-1 pic zzz. All line not containing the word pic I would call a group item and the other lines will be elementary items. I would like to wrote a routine(or program) that save each group item and the elementary items contained in a StringList. Admit that the pattern of the structure is random. The example above is only an example. In this example: StringList1 will contain 'a-1' '03 b-1 pic xxx.' '03 b-2 pic 999.' '03 b-4 pic zzz.' StringList2 will contain 'b-3' '05 c-1 pic aaa.' '05 c-3 pic 99.' StringList3 will contain 'c-2' '07 d-1 pic zzz.' '07 d-2 pic xxx.' StringList4 will contain 'b-5' '05 e-1 pic zzz.' At the end of the program I will(for example) write the StringList's to disk. But I can't write anyone before the program end. I had thinked hard about it. I can't create StringList with a variable name. I must previously declare each one in my pascal source. How can I solve the trouble proposed? I can't create StringList with a variable name. I don't know how much pascal experience you have. and I am not 100% sure what this line means, but taking a guess: You need a way to store stringlist2 in stringlist1 = So that if you later read the list, you can read the nested lists too? You do not need a variable for each Stringlist you create. Procedure AddNestedStringlist(OuterStringlist: TStringList; Text: String); var InnerStringList: TStringlist; begin InnerStringList := TStringlist.Create; OuterStringlist.AddObject(Text, InnerStringlist); end; Thats it. Note that there is no InnerStringlist.Free. The stringlist you created is not bound to the variable InnerStringlist. It is just a stringlist in memory, and any variable (of the correct type) can refer to it. To read the variable back (you need a type cast): NextedStringList := TStringList(OuterStringList.Objects[n]); Before you Free OuterStringlist, you have to check for any InnerStringlist and destroy it, or you will leak memory. Note that when I'm appending strings in a StringList, it's possible that I must create a new StringList(or various), put data in it(or them) and return to put data in the first StringList. If the solution is obvious I beg your pardon. I can't find it. * * ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
off-topic [Re: [fpc-pascal] proxy for sql]
Andreas Berger wrote: This isn't really a FPC question, but since the application is being written in FPC I thought I would ask here. I am developing an application that controls machinery. The application will store everything that happens in a SQL database. Some clients (restricted) should have permission to access the database to generate their own reports via some 3rd party report generation software of their choice. However I want to restrict who has access without placing a user password on the SQL server since some clients purchase multiple instances of the SW but not all options. 1) Is it possible to place my app between the 3rd party app and the SQL server? How would I do this. 2) Is it possible to configure the SQL server to query my app to see if a user can log on? 3) Any other ideas? Regards, Andreas Well I imagine that will be hard to do, if you do it in FPC (since you may have to start from scratch). I don't think there is a component emulating the mysql server interface. Rewriting the server (just the protocol part) is a lot of work. You may want to look at the mysql site, they have a mysql-proxy, which can be controlled by LUA script. So that my do the trick for you. You could probably replace the client credentials inside the proxy. Make sure you forward using a restricted account. Otherwise you must ensure that nothing in the sql could ever violate the permissions. Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] proxy for sql
Andreas Berger wrote: This isn't really a FPC question, but since the application is being written in FPC I thought I would ask here. I am developing an application that controls machinery. The application will store everything that happens in a SQL database. Some clients (restricted) should have permission to access the database to generate their own reports via some 3rd party report generation software of their choice. However I want to restrict who has access without placing a user password on the SQL server since some clients purchase multiple instances of the SW but not all options. 1) Is it possible to place my app between the 3rd party app and the SQL server? How would I do this. 2) Is it possible to configure the SQL server to query my app to see if a user can log on? 3) Any other ideas? Here is another idea. You would still need a user on the DB, to limit what can be accessed. But to check if access should be granted (allow or deny tcp) you can use your own software. All you need is some sort of Proxy/socket forwarder, that you can implement using FPC. The Tool would run on the users local PC or Server. It would accept connections for the database, and forward the Connection straight to the real DB (or maybe encrypt it, using whatever access control). Of course if the user is not allowed to connect at all, you do not make the forward. The user could have a key(public/private), so if you remove the opposite on the server, the user can no longer connect. However this acts like a tunnel, so you do not get any control on the SQL itself. The SQL server needs to be configured to restrict access to the permitted data. Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] csLoading and Create
Hi, If a component is loaded from a stream, then csLoading is set in ComponentState (or so I thought I understood the concept) So in my component i do if not(csLoading in componentState) ... However I found this does not work in the constructor Create. csLoading is only set *after* the Constructor has been called. (This is unless it is an inline component?). - TReader does create the object with class.NewInstance (so create is not yet called) - the for inlined components it does set csInline, scLoading = for others it does not set anything - then the constructor create is called (but csLoading is not set) - only then does csLoading get set Is this supposed to be like this? How else can I inside Create check if the component is loaded from a stream? Thanks Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] csLoading and Create
Michael Van Canneyt wrote: On Wed, 14 Jan 2009, Martin Friebe wrote: Hi, If a component is loaded from a stream, then csLoading is set in ComponentState (or so I thought I understood the concept) So in my component i do if not(csLoading in componentState) ... However I found this does not work in the constructor Create. csLoading is only set *after* the Constructor has been called. (This is unless it is an inline component?). - TReader does create the object with class.NewInstance (so create is not yet called) - the for inlined components it does set csInline, scLoading = for others it does not set anything - then the constructor create is called (but csLoading is not set) - only then does csLoading get set Is this supposed to be like this? How else can I inside Create check if the component is loaded from a stream? It is supposed to be like this. You cannot check this, and you shoud not. A component should always behave the same, no matter whether it is being streamed or not: You cannot a priori know whether a component of a certain class will be streamed or not. So here is my problem. I have a component, that may or may not have children. If it has children they are correctly streamed, and read back too. Historically it did not have children (or more accurate, it did, but they did not get streamed, they where constant) Now I want to make sure that: - a newly created (not loaded) component behaves as before. It creates it's default children. - a loaded component however can not do with this default created children = because they would be duplicates. Simply replacing isn't going to work, since their amount can vary. (0, 1 or more). In fact in Lazarus I probably going to check the LCLVersion property of the form (or something like that). = This is for loaded components = new componets always will have the default. In any way, currently this default children are created in the constructor, so it would have been nice to know if it was loaded or not. Question: - Is there a better place to create those defaults? One where I can access the necessary information? - Alternative ReadState comes to mind. I can intercept it, and clear out the defaults, since loading is about to happen. (then call inherited) Any better Idea? Another question: The component described are Subcomponents, and they are not visible. I will probably have them parented and owned by the same visible control. ( The only reason to stream them as component is because they vary in number and can be of different classes. I can not do that through a property, nor through a collection: Property is fixed in number and class Collection(Item) is fixed in class, only variable in number ) It seems to work with the default setting. But I was wondering if in such a scenario I should have to thing about csInline, csAncestor or csInherited? Probably not? Thanks and Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] SQL show tables
Joost van der Sluis wrote: Op maandag 12-01-2009 om 13:30 uur [tijdzone -0500], schreef David B Copeland: Query: Cannot open a non-select statement 'show tables' is not a valid sql-statement. It is a MySQL-hack. The TODBCConnection can not see that it is connected to a MySQL server and thus doesn't recognise this statement as a select-statement. If you use a TMySQLConnection it will work. You can fill in a bug report to ask if TODBCConnection can recognise 'show' as 'select'. We'll have to look what kind of effect that has on other (really sql-based) database-servers. If you (the original poster) uses Mysql 5 or up, then Show tables is not needed. Use the information-schema instead SELECT table_name FROM INFORMATION_SCHEMA.TABLES WHERE table_schema = '/|db_name|/' ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Saving user created component structure to LFM file
Hi, I may have found a way top solve my problem (saving a list of components from various places, not necesarely all nested in the top level component / See below) The question now is, how forward-compatible is this ode. How much do I have to expect any of the current code to change in ways that would break my solution? What I would do: The outer container has no nested components of it's own. It seems I can hook into (override) TComponent.WriteState which is calling WriteComponentData (properties, then Children). Since no children are there, I can make my own calls to WriteComponent from there, supplying all the components, of all the helper objects. On Read, I can Hook into ReadState. I can let the reader add them normally, and sort them out/once they have been read by the reader. I ReadState, I can also sort out to get rid of the default list of objects/components (since new ones are loaded). This must be in ReadState, not in Loaded, because Loaded is called after, and I would run into trouble making the diff between the default, and reloaded objects) The generated LFM file definitely looks like any LFM file (it has a component, with properties first then other nested Components) Any ideas, if this is a bad idea (like in will break soon)? Thanks Martin Martin Friebe wrote: Hi, I have a problem saving a certain component struicture to an LFM (lazarus) file and read it back. since a good amount of code is in FPC, I am not sure which list to go to? There is classes/writer.inc with has TBinaryObjectWriter. This is where things go first. Then, later this gets translated into text. This translation seems to be stricter in terms of what can be nested. Anyway the problem is, that if I want to save a component (that can be of different class/classes) then I can use WriteComponent. But only if I am in a Component that is itself written with WriteComponent. In the final LFM it seems a Component can only be nested in an other component. It does not seem to be possible to put it in: - Not in a subcomponent (because a subcomponent does not write it's class, but just the properties that are visible for the class given by the property property Foo: TPanel read .. write ... writes Foo.Name = 'abc' Foo.Top = 1 ... - Not in a TCollection, or at least I havent managed. Also again a TCollection is restricted to one classs for all Items - Not Using DefineProperties All propwerties with define property are of the kind Name = Value I can add a list, but even inside the list I can not write a component What I want to archive is theFollowing. I have TMainComponent = class (foo) property Options : TPersitentBar read x write x; end If It has to be it can be a TComponent, with SubComponent in TComponentStyle. Problem 1) Options is always created in the constructor, it can not be stored as a nested Component in the LFM. If it was, it would exist twice (once created in the constructor, and once loaded from the lfm) TPersitentBar should have a list of components, variable number, and different subclasses (could inherit from TPersistent, only Component if it makes it easier) How can I get this list saved into the lfm? Each item has a diff class, and diff properties, so they must saved via WriteComponent. (Which does not work for DefineProerties) And of course a default list of items is created in the constructor, so I need to detect if they are loaded, and remove the defaults. Any Idea? Example of the final structure (if only it was valid) object MainComp1 : TMainComponent Options.AllowFoo = 1 Options.AllowABC = 2 object Options.SubOptionsForCars : TCarOptions MAxCar = 4 end object Options.SubOptionsForTrains : TTrainOptions MAxTrain = 1 end end Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] Saving user created component structure to LFM file
Hi, I have a problem saving a certain component struicture to an LFM (lazarus) file and read it back. since a good amount of code is in FPC, I am not sure which list to go to? There is classes/writer.inc with has TBinaryObjectWriter. This is where things go first. Then, later this gets translated into text. This translation seems to be stricter in terms of what can be nested. Anyway the problem is, that if I want to save a component (that can be of different class/classes) then I can use WriteComponent. But only if I am in a Component that is itself written with WriteComponent. In the final LFM it seems a Component can only be nested in an other component. It does not seem to be possible to put it in: - Not in a subcomponent (because a subcomponent does not write it's class, but just the properties that are visible for the class given by the property property Foo: TPanel read .. write ... writes Foo.Name = 'abc' Foo.Top = 1 ... - Not in a TCollection, or at least I havent managed. Also again a TCollection is restricted to one classs for all Items - Not Using DefineProperties All propwerties with define property are of the kind Name = Value I can add a list, but even inside the list I can not write a component What I want to archive is theFollowing. I have TMainComponent = class (foo) property Options : TPersitentBar read x write x; end If It has to be it can be a TComponent, with SubComponent in TComponentStyle. Problem 1) Options is always created in the constructor, it can not be stored as a nested Component in the LFM. If it was, it would exist twice (once created in the constructor, and once loaded from the lfm) TPersitentBar should have a list of components, variable number, and different subclasses (could inherit from TPersistent, only Component if it makes it easier) How can I get this list saved into the lfm? Each item has a diff class, and diff properties, so they must saved via WriteComponent. (Which does not work for DefineProerties) And of course a default list of items is created in the constructor, so I need to detect if they are loaded, and remove the defaults. Any Idea? Example of the final structure (if only it was valid) object MainComp1 : TMainComponent Options.AllowFoo = 1 Options.AllowABC = 2 object Options.SubOptionsForCars : TCarOptions MAxCar = 4 end object Options.SubOptionsForTrains : TTrainOptions MAxTrain = 1 end end Best Regards Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementation [off topic - goto ?]
Vinzent Höfler wrote: Jürgen Hestermann wrote: Mantra: First make it work, then make it fast. In general that's true from the programmer's viewpoint. But this does not apply to adding language details because there is no 'first make it work'. Why obscure important implementation details if the only benefit is saving some writing? I won't judge on the only save some writing here, but generally it *does* apply to language features: If a particular language feature helps you writing correct code faster (by supporting you to make it work instead of relying on your abilities to use the debugger), then it does apply. The real question is if the (or any other) proposal is good enough to do just that, or if it's really some syntactic sweetener (not even sugar, sugar at least contains energy). That's something to discuss. Let me take a rather extreme point of view: After all, all those for-, while-, and repeat-until-loops are only there to save you from some typing work[0], because Pascal already has a perfectly good loop-construct with which you can do all that: goto. Would you agree here? Probably not. 1) goto alone (labels assumed) can not replace any of the loop constructs. It must be paired with if (or anything to check conditions) 2) Otherwise you are of course right. Following this logic however most programming languages (including pascal and assembler) become redundant. They have far to many instructions to archive the same thing. Look at languages like whitespace or brainfuck and you will see that a language which is kept simple (by the meaning of no unneeded instructions does not need more than 6 to 8 instructions. SCNR. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
[fpc-pascal] a few installation issues (trunc on freebsd)
I have a few question, regarding my attempts to install fpc from trunc (I read the build faq, yet I have not succeeded...) On a freebsd (7.0) box, I have downloaded and installed the pre-compiled fpc 2.2.2 ( to use as my initial compiler.) I have created my workind dir /data/fpc_trunc/svn and done my checkout (Revision: 12021) cd /data/fpc_trunc/snv svn co http://svn.freepascal.org/svn/fpc/trunk . then according to the build-faq, I have done cd compiler gmake cycle * First problem: I found if I simply go to the parent (svn) directory, and do a gmake all PP=/data/fpc_trunc/svn/compiler/ppc386 there, it will do some clean out, and stop because halfway through it will have deleted this compiler. So instead (which is not mentioned in the buildfaq?), I have installed the compiler and rtl at this stage: gmake install INSTALL_PREFIX=/data/fpc_trunc/inst/ cd ../rtl gmake install INSTALL_PREFIX=/data/fpc_trunc/inst/ Note: I am installing to a separate dir, as I want to use this installation in parallel to other installations. * Second Problem: when using fpc (instead of ppc), it will always find the ppc386 in the default installation. The only way I can change this is fpc -Xp/path/to/my/ppc386. (Which I found no documentation for. I got that from looking through the source) However, if I want to use fpc from lazarus, I may not be able to pass that (convenient) on the command line. Is there any INI file? (fpc.cfg did not help here, at least not the fpc.cfg in the same path as fpc exe). Or is it save to substitute fpc, with ppc386 everywhere it is called? any way I then go and create my fpc.cfg: cd ../../inst ./bin/fpcmkcfg -d basepath=/data/fpc_trunc/inst/lib/fpc/2.2.2 bin/fpc.cfg * 3rd problem, it uses the same prefix for the units (-Fu) and the bin (-FD), so the above creates correct -Fu config, but I must change the -FD conf. Any solution to this ? -Fu will be correct: -Fu/data/fpc_trunc/inst/lib/fpc/2.2.2/units/$FPCTARGET/rtl but -FD will *NOT* be (which I think it should?, or am I wrong?) -FD/data/fpc_trunc/inst/bin now I go back to the top svn checkout and to gmake all PP=/data/fpc_trunc/inst/lib/fpc/2.2.2/ppc386 * 4th Problem the compilation aborted (Sorry I don't remember where) because it tried to access the x11 package = I did solve that by going int packages/x11, did the make there, and did install it (with the install prefix) * 5th problem packages/graph stops, because it tries to use x86. (This exists in the sources rtl/unix/x86.pp) Somehow all the above has not installed this (not on my FreeBSD), the package is missing int he inst/lib directory And last not least, having checked out trunc (or being under the impression to have done so), why has the make install in the rtl installed something with 2.2.2 in the path? (If I run the ppc386 that was installed it will say 2.3.1. Maybe this last bit will solve some of the other questions... Any help is greatly appreciated. Many thanks. Martin ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] a few installation issues (trunc on freebsd)
Thanks for the help below. Here is the x86 related error. I did (working directory: /data/fpc_trunc/svn ) svn up svn info Path: . URL: http://svn.freepascal.org/svn/fpc/trunk Repository Root: http://svn.freepascal.org/svn/fpc Repository UUID: 3ad0048d-3df7-0310-abae-a5850022a9f2 Revision: 12025 Node Kind: directory Schedule: normal Last Changed Author: jonas Last Changed Rev: 12025 Last Changed Date: 2008-11-03 21:18:27 + (Mon, 03 Nov 2008) gmake distclean gmake all The last lines from this make are below. At this stage it is using ppc386 from the cvn directory, and it is also using the rtl from svn. /data/fpc_trunc/svn/compiler/ppc386 -V Free Pascal Compiler version 2.3.1 [2008/11/03] for i386 Copyright (c) 1993-2008 by Florian Klaempfl The Error, I get gmake[3]: Leaving directory `/data/fpc_trunc/svn/packages/openssl' gmake -C graph smart gmake[3]: Entering directory `/data/fpc_trunc/svn/packages/graph' gmake all LINKSMART=1 CREATESMART=1 gmake[4]: Entering directory `/data/fpc_trunc/svn/packages/graph' /bin/mkdir -p units/i386-freebsd /data/fpc_trunc/svn/compiler/ppc386 -XX -CX -Ur -Xs -O2 -n -S2 -Fu/data/fpc_trunc/svn/rtl/units/i386-freebsd -Fu/data/fpc_trunc/svn/packages/pthreads/units/i386-freebsd -Fu/data/fpc_trunc/svn/packages/x11/units/i386-freebsd -Fu/data/fpc_trunc/svn/packages/sdl/units/i386-freebsd -Fisrc/freebsd -Fisrc/inc -Fisrc/unix -FE. -FUunits/i386-freebsd -di386 -dRELEASE -Isrc/inc src/unix/graph.pp Fatal: Can't find unit x86 used by Graph Fatal: Compilation aborted gmake[4]: *** [graph.ppu] Error 1 gmake[4]: Leaving directory `/data/fpc_trunc/svn/packages/graph' gmake[3]: *** [fpc_smart] Error 2 gmake[3]: Leaving directory `/data/fpc_trunc/svn/packages/graph' gmake[2]: *** [graph_smart] Error 2 gmake[2]: Leaving directory `/data/fpc_trunc/svn/packages' gmake[1]: *** [packages_smart] Error 2 gmake[1]: Leaving directory `/data/fpc_trunc/svn' gmake: *** [build-stamp.i386-freebsd] Error 2 Any idea? But thanks for the hint on make install gmake install FPC=xxx INSTALL_PREFIX=foo worked well (created a 2.3.1 dir) Same if I use PP= instead of FPC=. Is there a difference? I looked at the buildfaq at http://www.stack.nl/~marcov/buildfaq.pdf (not sure if this is up to date?) Chapter 2, pages 22: The first 2 examples have make install with *no* PP=. Of course my fault, I didn't read properly. It then explains that they are wrong. Maybe it would be easier for users to follow if either no wrong examples where given, or maybe the hint # wrong example was given on the same line as the command. So you would more liekly get to read it, if you copied and pasted it? I know it's my fault not to read it proper. But i could imagine, that othere may get into similar trouble... Thanks Martin Jonas Maebe wrote: On 03 Nov 2008, at 16:03, Martin Friebe wrote: I have a few question, regarding my attempts to install fpc from trunc Small aside: it's trunk (as in trunk of a tree, compared to branches), not trunc (as in truncate). * First problem: I found if I simply go to the parent (svn) directory, and do a gmake all PP=/data/fpc_trunc/svn/compiler/ppc386 there, it will do some clean out, and stop because halfway through it will have deleted this compiler. That's correct. So instead (which is not mentioned in the buildfaq?), I have installed the compiler and rtl at this stage: gmake install INSTALL_PREFIX=/data/fpc_trunc/inst/ cd ../rtl gmake install INSTALL_PREFIX=/data/fpc_trunc/inst/ You don't have to install the compiler/rtl. You only have to copy the compiler binary someplace safe. In face, you don't need the cycle at all, you can immediately do a gmake all. * Second Problem: when using fpc (instead of ppc), it will always find the ppc386 in the default installation. The only way I can change this is fpc -Xp/path/to/my/ppc386. (Which I found no documentation for. I got that from looking through the source) However, if I want to use fpc from lazarus, I may not be able to pass that (convenient) on the command line. Does lazarus call fpc or ppcXXX? Is there any INI file? No. (fpc.cfg did not help here, at least not the fpc.cfg in the same path as fpc exe). Or is it save to substitute fpc, with ppc386 everywhere it is called? Yes, that's safe. any way I then go and create my fpc.cfg: cd ../../inst ./bin/fpcmkcfg -d basepath=/data/fpc_trunc/inst/lib/fpc/2.2.2 bin/fpc.cfg I'm not sure how well maintained fpcmkcfg is. For the (*nix) releases we use the samplecfg script (from compiler/utils) to generate configurations. But you shouldn't need a new configuration file, afaik samplecfg is identical in fixes and trunk (and in 2.2.2). * 3rd problem, it uses the same prefix for the units (-Fu) and the bin (-FD), so the above creates correct -Fu config, but I must change the -FD conf. Any solution to this ? -Fu will be correct: -Fu/data/fpc_trunc/inst/lib/fpc/2.2.2/units/$FPCTARGET/rtl but -FD will *NOT* be (which I think it should?, or am I wrong
