std.getopt and std.datetime
Is there a canonical, idiomatic way of processing std.datetime objects using std.getopt? Currently, I am suffering: /usr/include/d/std/getopt.d(921): Error: static assert "Dunno how to deal with type SysTime*" which on the one hand is understandable, albeit dreadful English, but then I suppose it is American not English, as std.getopt is only going to process builtin types, but it is very annoying. -- Russel. = Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Roadm: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder signature.asc Description: This is a digitally signed message part
Re: Access specifiers and visibility
On Thursday, 11 May 2017 at 04:35:22 UTC, Jesse Phillips wrote: On Wednesday, 10 May 2017 at 13:29:40 UTC, Andrew Edwards wrote: On Wednesday, 10 May 2017 at 13:13:46 UTC, Jesse Phillips wrote: On Wednesday, 10 May 2017 at 01:42:47 UTC, Andrew Edwards wrote: Attempting to update a git repo to current D, I encounter the following deprecation messages: src/glwtf/signals.d-mixin-256(256,2): Deprecation: glwtf.input.BaseGLFWEventHandler._on_key_down is not visible from module glwtf.signals Thanks, Andrew This comes from: http://dlang.org/changelog/2.071.0.html#dip22 The module glwtf.signals needs to import glwtf.input. One of the other imports was contaminating the namespace. I actually attempted solve the issue with selective import as such:: import glwtf.input : BaseGLFWEventHandler; but it did not work. Importing the entire module does not work either. I'm not sure the library you're using but this like the one: https://github.com/Dav1dde/glwtf/blob/master/glwtf/input.d#L163 This code says that the function is protected. https://github.com/Dav1dde/glwtf/blob/master/glwtf/signals.d#L254 This line is probably mixing in a call to that function into a struct https://github.com/Dav1dde/glwtf/blob/master/glwtf/signals.d#L229 But that struct doesn't inherit from the class so it can't access protected fields. That's not the same library but the exact same implementation. The one I'm using (https://github.com/d-gamedev-team/dimgui) borrows its from the deimos bindings. So since the a struct cannot inherit from a class and vice versa, then the entire approach taken by the library must be reconsidered going forward. A little over my head at this point. Thanks for the assist.
Re: How to avoid throwing an exceptions for a built-in function?
On Thursday, 11 May 2017 at 16:07:22 UTC, k-five wrote:
On Wednesday, 10 May 2017 at 21:19:21 UTC, Stanislav Blinov
wrote:
On Wednesday, 10 May 2017 at 15:35:24 UTC, k-five wrote:
On Wednesday, 10 May 2017 at 14:27:46 UTC, Stanislav Blinov
---
I don't understand. If you don't want to take care of
exceptions, then you just don't do anything, simply call
to!int(str).
Well I did that, but when the string is a valid type like: "10"
there is no problems. But when the string is not valid, like:
"abc", then to! function throws an exception.
Why I do not want to take care of that? Because I just need the
value, if the string is valid, otherwise no matter what the
value of string is.
First I just wrote:
index = to!int( user_apply[ 4 ] );
And this code is a part of a command-line program and the user
may enter anything. So, for a valid string:
./program '10' // okey
but for:
./program 'non-numerical' // throws an exception an 10 lines of
error appear on the screen( console )
I just want to silent this exception. Of course it is useful
for handling when someone wants to. But in my code I no need to
handle it. So I want to silent that, without using
try{}catch(){} block. I just wondered about try-catch and I
want to know may there would be a better way instead of a dummy
try-catch block.
Thanks for replying and mentioning. And I am sorry, since I an
new in English Writing, if you got confuse.
You are not making a lot of sense:
1. Exception do bubble up, so you don't need to "handle"
exceptions at the call site if you don't want to. The whole point
of exceptions is do effectively do what you want.
2. You say that you don't have to deal with it in your code but
you are trying to deal with it now.
You are not clear on exactly what you are trying to accomplish.
Can you be more specific on why you do not want to add a
try/catch/if-else/ifThrown/etc? Is it because you don't need to
handle it in your own usage? If that is true, will others ever
use it?
Basically all you have to do is ask yourself this:
"Do I need to EVER handle the case where the data is invalid?"
If you do(e.g., other users will use your code) then you better
implement some type of exception handling. Else all you have to
do is always put in the right data(not good because it might bite
you in the ass one day).
If you just want less noise when the program crashes, just put a
try/catch block in main and catch all generic exceptions and exit
with a simple error message like "There was an ERROR, I do not
know why...".
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 21:26:01 UTC, Bastiaan Veelo wrote: On Friday, 12 May 2017 at 15:24:52 UTC, k-five wrote: A full version that I just added to my gitgub: https://github.com/k-five/dren You may like getopt[1] for command line argument parsing. https://dlang.org/phobos/std_getopt.html see also https://blog.thecybershadow.net/2014/08/05/ae-utils-funopt/ https://github.com/CyberShadow/ae/blob/master/utils/funopt.d
Re: Lookahead in unittest
On Fri, May 12, 2017 at 05:23:23PM -0400, Steven Schveighoffer via
Digitalmars-d-learn wrote:
[...]
> Note, you can achieve what you want with version(unittest):
>
> version(unittest)
> {
>class A { B b; }
>class B { }
> }
>
> unittest
> {
>// use A and B here
> }
[...]
This advice, unfortunately, needs to be tempered with caution about
namespace pollution and accidental dependency of things outside
unittests on things inside a version(unittest) block. There's also the
issue of library code introducing extraneous import dependencies that
are really only necessary for unittesting, but get pulled in anyway
because user code happens to compile with -unittest.
T
--
"Real programmers can write assembly code in any language. :-)" -- Larry Wall
Re: Lookahead in unittest
On Friday, 12 May 2017 at 21:23:23 UTC, Steven Schveighoffer
wrote:
Note, you can achieve what you want with version(unittest):
Please prefer `private version(unittest){...}` if the module
might be imported by someone else's code, as to not pollute it
with unneeded symbols
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 15:24:52 UTC, k-five wrote: A full version that I just added to my gitgub: https://github.com/k-five/dren You may like getopt[1] for command line argument parsing. https://dlang.org/phobos/std_getopt.html
Re: Lookahead in unittest
On 5/10/17 12:53 PM, Raiderium wrote:
On Wednesday, 10 May 2017 at 16:32:11 UTC, Adam D. Ruppe wrote:
On Wednesday, 10 May 2017 at 16:09:06 UTC, Raiderium wrote:
I can't figure out if this is intended behaviour.
It is. A unittest is a function, and in functions, all declarations
must be defined before used (just like local variables).
Sometimes, you can wrap it in a struct:
unittest {
struct Decls {
// put your decls here
}
with(Decls()) {
// call funcs here
}
}
Ah. I wasn't aware class declarations within functions (including
unittest) were sensitive to their order, so that's something I've
learned today. :)
I tried the with(Decls()) syntax and it worked perfectly, thanks Adam.
I'd been haphazardly nesting unittest{} blocks within the struct, and it
felt less than sanitary.
For full disclosure, the test I'm writing needs to create a reference
cycle (as in, class B holding a reference to A), and it works properly
if the classes are declared at module/class/struct level, but then
either the class names pollute the module (which is just eww) or they're
nested within a class/struct, which leads me to the current situation.
Consider my problem solved :) Thanks again Stefan and Adam for the replies.
Note, you can achieve what you want with version(unittest):
version(unittest)
{
class A { B b; }
class B { }
}
unittest
{
// use A and B here
}
-Steve
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 15:24:52 UTC, k-five wrote:
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
I was waiting for a stable version of C++17 ( standard library
) to add some features of fileSystem in C++17 to my program
that wants to iterate through all files in a directory
recursively.
I was thinking how could I do for implementing that and add it
to my program.
Now after starting to learn D ( nearby 2 weeks so far ). I can
do it in 6 lines!
void main( string[] args ){
string[] all_file_name = dirEntries( ".", SpanMode.depth,
false )
.filter!( file => !file.name.matchFirst( regex( args[
1 ] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.array;
foreach( string item; all_file_name ) writeln( item );
}
./bin-file '[A-Z]$' -f ---> print all files that are matched
against [A-Z]$
./bin-file '[A-Z]$' -d ---> print all directory that are
matched against [A-Z]$
./bin-file '[A-Z]$' "anything-else" ---> print both files and
directory that are matched against [A-Z]$
I am so happy since after more than one year practicing in C++
and putting a collection more than 2000 examples of C++ on my
github, I was not sure I could do it in 6 lines.
May it is a Spam but I think it is worth it.
--
May it has worth it to be an example on how great D is, in
somewhere like, in the tour section or std.file or std.regex to
attract others.
A full version that I just added to my gitgub:
https://github.com/k-five/dren
Is it safe to say that these 40 lines of D do the same as your
324 lines of C++ [1]? This, and your comments on the difficulties
of building renrem [2] versus doing "rdmd", and the steepness of
the learning curve (1 year C++ vs 2 weeks D), and the
productivity (2 hours D vs ?? C++) I think are plenty material
for a nice little blog.
Mike Parker runs the D blog, and I think he might be interested.
No need to worry about the english language, you are safe with
Mike. I'll see if I can get you his attention.
[1] https://github.com/k-five/renrem
[2] https://github.com/k-five/renrem/blob/master/src/README.md
[3] https://dlang.org/blog/
Re: How to avoid throwing an exceptions for a built-in function?
On Fri, May 12, 2017 at 12:47:04PM +0200, ag0aep6g via Digitalmars-d-learn wrote: > On 05/12/2017 10:32 AM, k-five wrote: > > Interesting! I was worried about performance and for that I did not > > want to use try-catch. > > So (isNumberic) is a good solution. > > http://dlang.org/phobos/std_traits.html#isNumeric > > If you're doing this for speed, you better be benchmarking. Exceptions > are slow when they're thrown. But if no exception is being thrown, > try-catch is probably faster than checking isNumeric beforehand. Yes, when it comes to performance-related issues, always profile, profile, profile. (Or benchmark, benchmark, benchmark. Anything that gives you actual measurements rather than subjective judgment calls.) Far too often, what we think will perform poorly is actually nowhere near the real bottleneck in the program, and we end up wasting too much time "optimizing" something that doesn't even make a noticeable difference in the end. Whereas, using a profiler early on will help you zero in on the real bottlenecks, and you could potentially make huge performance savings with much less effort. T -- Beware of bugs in the above code; I have only proved it correct, not tried it. -- Donald Knuth
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
I was waiting for a stable version of C++17 ( standard library
) to add some features of fileSystem in C++17 to my program
that wants to iterate through all files in a directory
recursively.
I was thinking how could I do for implementing that and add it
to my program.
Now after starting to learn D ( nearby 2 weeks so far ). I can
do it in 6 lines!
void main( string[] args ){
string[] all_file_name = dirEntries( ".", SpanMode.depth,
false )
.filter!( file => !file.name.matchFirst( regex( args[
1 ] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.array;
foreach( string item; all_file_name ) writeln( item );
}
./bin-file '[A-Z]$' -f ---> print all files that are matched
against [A-Z]$
./bin-file '[A-Z]$' -d ---> print all directory that are
matched against [A-Z]$
./bin-file '[A-Z]$' "anything-else" ---> print both files and
directory that are matched against [A-Z]$
I am so happy since after more than one year practicing in C++
and putting a collection more than 2000 examples of C++ on my
github, I was not sure I could do it in 6 lines.
May it is a Spam but I think it is worth it.
--
May it has worth it to be an example on how great D is, in
somewhere like, in the tour section or std.file or std.regex to
attract others.
A full version that I just added to my gitgub:
https://github.com/k-five/dren
Re: Processing a gzipped csv-file by line-by-line
On 5/11/17 8:18 PM, H. S. Teoh via Digitalmars-d-learn wrote: On Wed, May 10, 2017 at 11:40:08PM +, Jesse Phillips via Digitalmars-d-learn wrote: If you can get the zip to decompress into a range of dchar then std.csv will work with it. It is by far not the fastest, but much speed is lost since it supports input ranges and doesn't specialize on any other range type. I actually spent some time today to look into whether fastcsv can possibly be made to work with general input ranges as long as they support slicing... and immediately ran into the infamous autodecoding issue: strings are not random-access ranges because of autodecoding, so it would require either extensive code surgery to make it work, or ugly hacks to bypass autodecoding. I'm quite tempted to attempt the latter, in fact, but not now since it's getting busier at work and I don't have that much free time to spend on a major refactoring of fastcsv. Yeah, iopipe treats char[] as a random-access sliceable range :) Autodecoding gets annoying if you want to do anything fancy (like chain(somestr, someotherstr)) Alternatively, I could possibly hack together a version of fastcsv that took a range of const(char)[] as input (rather than a single string), so that, in theory, it could handle arbitrarily large input files as long as the caller can provide a range of data blocks, e.g., File.byChunk, or in this particular case, a range of decompressed data blocks from whatever decompressor is used to extract the data. As long as you consume the individual rows without storing references to them indefinitely (don't try to make an array of the entire dataset), fastcsv's optimizations should still work, since unreferenced blocks will eventually get cleaned up by the GC when memory runs low. I'm interested in getting a fast CSV parser built on top of iopipe. I may fork your code and see if I can get it to work. Since you already work on arrays, it should be quite simple, since arrays are also iopipes by default. -Steve
Re: Processing a gzipped csv-file by line-by-line
On 5/10/17 7:17 PM, Nicholas Wilson wrote: On Wednesday, 10 May 2017 at 22:20:52 UTC, Nordlöw wrote: What's fastest way to on-the-fly-decompress and process a gzipped csv-fil line by line? Is it possible to combine http://dlang.org/phobos/std_zlib.html with some stream variant of File(path).byLineFast ? I suggest you take a look at Steven's iopipe (also watch his Dconf presentation). should be very simple. Yeah, this should work and be quite fast: import iopipe.zip; import iopipe.textpipe; import iopipe.bufpipe; import iopipe.stream; foreach(line; openDev(path).bufd.unzip.decodeText.byLineRange) I think that was actually one of my slide examples. -Steve
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 12:56:50 UTC, drug wrote: 12.05.2017 14:58, k-five пишет: On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote: On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote: --- also .each!writeln should be possible - Yes. Worked. Thanks
Re: As many thanks As possible to who crates D and UFCS feature
12.05.2017 14:58, k-five пишет:
On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
---
Shorter:
void main( string[] args ){
dirEntries( ".", SpanMode.depth, false )
.filter!( file => !file.name.matchFirst( regex( args[ 1 ] )
).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d" ?
( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink
) ) )
.map!( file => file.name )
.each!(string item => writeln( item ));
}
It's more memory efficient too because at no point the actual list is
stored.
-
Thanks and the correct syntax for each! is, passing a lambda. So the:
.each!(string item => writeln( item ));
is an error:
temp.d(15): Error: found 'item' when expecting ')' following template
argument list ...
and should be:
.each!( ( string item ) => writeln( item ) );
also .each!writeln should be possible
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote: I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively. I was thinking how could I do for implementing that and add it to my program. Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines! Thumbs up, nice post! Bastiaan.
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 11:58:23 UTC, k-five wrote: On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote: [...] --- [...] - Thanks and the correct syntax for each! is, passing a lambda. So the: [...] is an error: temp.d(15): Error: found 'item' when expecting ')' following template argument list ... and should be: .each!( ( string item ) => writeln( item ) ); Ah, yeah, my bad, I should have try compiling it instead of answering directly ;)
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
---
Shorter:
void main( string[] args ){
dirEntries( ".", SpanMode.depth, false )
.filter!( file => !file.name.matchFirst( regex( args[
1 ] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.each!(string item => writeln( item ));
}
It's more memory efficient too because at no point the actual
list is stored.
-
Thanks and the correct syntax for each! is, passing a lambda. So
the:
.each!(string item => writeln( item ));
is an error:
temp.d(15): Error: found 'item' when expecting ')' following
template argument list ...
and should be:
.each!( ( string item ) => writeln( item ) );
Re: As many thanks As possible to who crates D and UFCS feature
On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
I was waiting for a stable version of C++17 ( standard library
) to add some features of fileSystem in C++17 to my program
that wants to iterate through all files in a directory
recursively.
I was thinking how could I do for implementing that and add it
to my program.
Now after starting to learn D ( nearby 2 weeks so far ). I can
do it in 6 lines!
void main( string[] args ){
string[] all_file_name = dirEntries( ".", SpanMode.depth,
false )
.filter!( file => !file.name.matchFirst( regex( args[
1 ] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.array;
foreach( string item; all_file_name ) writeln( item );
}
./bin-file '[A-Z]$' -f ---> print all files that are matched
against [A-Z]$
./bin-file '[A-Z]$' -d ---> print all directory that are
matched against [A-Z]$
./bin-file '[A-Z]$' "anything-else" ---> print both files and
directory that are matched against [A-Z]$
I am so happy since after more than one year practicing in C++
and putting a collection more than 2000 examples of C++ on my
github, I was not sure I could do it in 6 lines.
May it is a Spam but I think it is worth it.
Shorter:
void main( string[] args ){
dirEntries( ".", SpanMode.depth, false )
.filter!( file => !file.name.matchFirst( regex( args[ 1
] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.each!(string item => writeln( item ));
}
It's more memory efficient too because at no point the actual
list is stored.
As many thanks As possible to who crates D and UFCS feature
I was waiting for a stable version of C++17 ( standard library )
to add some features of fileSystem in C++17 to my program that
wants to iterate through all files in a directory recursively.
I was thinking how could I do for implementing that and add it to
my program.
Now after starting to learn D ( nearby 2 weeks so far ). I can do
it in 6 lines!
void main( string[] args ){
string[] all_file_name = dirEntries( ".", SpanMode.depth, false
)
.filter!( file => !file.name.matchFirst( regex( args[ 1
] ) ).empty() )
.filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] ==
"-d" ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : (
!file.isSymlink ) ) )
.map!( file => file.name )
.array;
foreach( string item; all_file_name ) writeln( item );
}
./bin-file '[A-Z]$' -f ---> print all files that are matched
against [A-Z]$
./bin-file '[A-Z]$' -d ---> print all directory that are
matched against [A-Z]$
./bin-file '[A-Z]$' "anything-else" ---> print both files and
directory that are matched against [A-Z]$
I am so happy since after more than one year practicing in C++
and putting a collection more than 2000 examples of C++ on my
github, I was not sure I could do it in 6 lines.
May it is a Spam but I think it is worth it.
Re: How to avoid throwing an exceptions for a built-in function?
On 05/12/2017 10:32 AM, k-five wrote: Interesting! I was worried about performance and for that I did not want to use try-catch. So (isNumberic) is a good solution. http://dlang.org/phobos/std_traits.html#isNumeric If you're doing this for speed, you better be benchmarking. Exceptions are slow when they're thrown. But if no exception is being thrown, try-catch is probably faster than checking isNumeric beforehand.
Re: How to avoid throwing an exceptions for a built-in function?
On Friday, 12 May 2017 at 09:03:39 UTC, Jonathan M Davis wrote: That's the wrong isNumeric. Unfortunately, both std.string and std.traits have an isNumeric. std.traits.isNumeric is an eponymous template that tests whether a type is an integral or floating point type, whereas std.string.isNumeric is a templated function which tests whether a string (or other range of characters) represents an integer or floating point literal. So, std.traits.isNumeric won't work at all for what you want, and std.string.isNumeric will sort of do what you want - the main caveat being that it will also accept floating point values, whereas to!int will not. So, if you have auto i = str.isNumeric ? to!int(str).ifThrown(0) : 0; then it will work but will still throw (and then be caught by ifThrown) if str is a floating point value. Alternatively, you could check something like auto i = str.all!isDigit ? to!int(str).ifThrown(0) : 0; (where all is in std.algorithm and isDigit is in std.ascii), and that _almost_ wouldn't need ifThrown, letting you do auto i = str.all!isDigit ? to!int(str) : 0; except that str could be an integral value that wouldn't fit in an int, in which case to!int would throw. But std.string.isNumeric will work so long as you're willing to have have an exception be thrown and caught if the string is a floating point literal. - Jonathan M Davis - Thank you for mentioning it. Since I had seen D-conference 2016 in YouTube and it talked about isNumeric in std.traits, then I used std.traits. and does not worked as I wanted. But std.string: isNumeric, worked. string str = "string"; int index = str.isNumeric ? to!int( str ) : 0; writeln( "index: ", index ); // 0 and without throwing any exceptions
Re: How to avoid throwing an exceptions for a built-in function?
On Friday, May 12, 2017 08:32:03 k-five via Digitalmars-d-learn wrote: > On Thursday, 11 May 2017 at 19:59:55 UTC, Jordan Wilson wrote: > > On Thursday, 11 May 2017 at 18:07:47 UTC, H. S. Teoh wrote: > >> On Thu, May 11, 2017 at 05:55:03PM +, k-five via > >> > >> Digitalmars-d-learn wrote: > >>> On Thursday, 11 May 2017 at 17:18:37 UTC, crimaniak wrote: > >>> > On Wednesday, 10 May 2017 at 12:40:41 UTC, k-five wrote: > >>> - > > > > This reason is why I sometimes use isNumeric if I have heaps of > > strings I need to convert, to reduce exceptions. So something > > like: > > int index = (str.isNumeric) ? to!int(str).ifThrown(0) : 0; > > > > Jordan > > -- > Interesting! I was worried about performance and for that I did > not want to use try-catch. > So (isNumberic) is a good solution. > http://dlang.org/phobos/std_traits.html#isNumeric That's the wrong isNumeric. Unfortunately, both std.string and std.traits have an isNumeric. std.traits.isNumeric is an eponymous template that tests whether a type is an integral or floating point type, whereas std.string.isNumeric is a templated function which tests whether a string (or other range of characters) represents an integer or floating point literal. So, std.traits.isNumeric won't work at all for what you want, and std.string.isNumeric will sort of do what you want - the main caveat being that it will also accept floating point values, whereas to!int will not. So, if you have auto i = str.isNumeric ? to!int(str).ifThrown(0) : 0; then it will work but will still throw (and then be caught by ifThrown) if str is a floating point value. Alternatively, you could check something like auto i = str.all!isDigit ? to!int(str).ifThrown(0) : 0; (where all is in std.algorithm and isDigit is in std.ascii), and that _almost_ wouldn't need ifThrown, letting you do auto i = str.all!isDigit ? to!int(str) : 0; except that str could be an integral value that wouldn't fit in an int, in which case to!int would throw. But std.string.isNumeric will work so long as you're willing to have have an exception be thrown and caught if the string is a floating point literal. - Jonathan M Davis
Re: How to avoid throwing an exceptions for a built-in function?
On Friday, 12 May 2017 at 08:32:03 UTC, k-five wrote: On Thursday, 11 May 2017 at 19:59:55 UTC, Jordan Wilson wrote: On Thursday, 11 May 2017 at 18:07:47 UTC, H. S. Teoh wrote: On Thu, May 11, 2017 at 05:55:03PM +, k-five via Digitalmars-d-learn wrote: On Thursday, 11 May 2017 at 17:18:37 UTC, crimaniak wrote: > On Wednesday, 10 May 2017 at 12:40:41 UTC, k-five wrote: - This reason is why I sometimes use isNumeric if I have heaps of strings I need to convert, to reduce exceptions. So something like: int index = (str.isNumeric) ? to!int(str).ifThrown(0) : 0; Jordan -- Interesting! I was worried about performance and for that I did not want to use try-catch. So (isNumberic) is a good solution. http://dlang.org/phobos/std_traits.html#isNumeric NOT a GOOD solution! Since it accept type and NOT variable: so: index = (str.isNumeric) ? to!int(str).ifThrown(0) : 0; is: temp.d(11): Error: template std.traits.isNumeric cannot deduce function from argument types !()(string), candidates are:
Re: How to avoid throwing an exceptions for a built-in function?
On Thursday, 11 May 2017 at 19:59:55 UTC, Jordan Wilson wrote: On Thursday, 11 May 2017 at 18:07:47 UTC, H. S. Teoh wrote: On Thu, May 11, 2017 at 05:55:03PM +, k-five via Digitalmars-d-learn wrote: On Thursday, 11 May 2017 at 17:18:37 UTC, crimaniak wrote: > On Wednesday, 10 May 2017 at 12:40:41 UTC, k-five wrote: - This reason is why I sometimes use isNumeric if I have heaps of strings I need to convert, to reduce exceptions. So something like: int index = (str.isNumeric) ? to!int(str).ifThrown(0) : 0; Jordan -- Interesting! I was worried about performance and for that I did not want to use try-catch. So (isNumberic) is a good solution. http://dlang.org/phobos/std_traits.html#isNumeric
