Also i have more 'intel' on the problem form questions i posted elsewhere.
I will serve as a conduit for this and try to keep every place update to the
latest developments. In the end i think it will create a kind of cohesion
between ideas, hopefully enough to generate something real.
Here goes:
First advice: You should use the debugger to go to the "edge" of the
logic inside your code and "code from there" onwards.
"The easiest way to figure that out is to debug the code and follow the
execution step by step.
Note that you can basically develop in the debugger, unlike most other
programming languages!
There are two ways to launch the debugger:
1. put a "self halt" in the code, this is the Smalltalk way of adding a
breakpoint
2. Select a piece of code and debug it, right click and select debug "
Second advice: It should make execution clear to the user.
"Essentially showing the execution order of any smalltalk code. I wanted to use
the "way" pharo works itself to do this… instead of parsing the text myself and
checking.
For example… in the Workspace… i can write a small piece of code that does
something. When i select it and click Do It. Pharo goes on to execute the text…
it first parses it i think and then figures out what to execute first and then
pass the product of that object to the next thing and so on.
It might look like this
something dothis.
anotherobject something dothis.
finalobject [ anotherobject something do this ]."
Third advice: Go in and do this after the code is compiled, this will
give exact data of that the code really compiles to and not just a layer that
parses text.
"http://smalltalkhub.com/#!/~dh83/ast-interpreter
There is a configuration and a lot of tests which document how it works.
There you have complete control over what is executed where.
Simply override the method that handles sends and you should be able to easily
add the things you want."
Forth advice: Showing the execution order as you create code, should
also work for illegal code so you can can create without the backfire of an
error (works best with dynamically typed languages) and this to be done
"debugger" style at the very edge of the logic in your code, this is where you
create… and should have a free but "helped and guided" hand.
"1. If you want to show the order of the messages sent *without* actually
executing the code you need to compile the code and inspect the AST.
This is not that hard to do.
2. If you want to visualize the order while executing it - you could
look at how Debugger works and simply "debug" the code programmatically.
It basically means spawning a Process and sending "step" to it over and
over and looking at where it is etc. Funky enough the Debugger is "just
Smalltalk code". :)
But what happens if the code does not exist, class names are not valid, method
names are just examples.
If i were to analyze something like an example someone has posted somewhere.
In Squeak I can't say, but in Pharo, the Compiler can be "stupid" and compile
more or less everything :)
So to get this "execution order" and no run-time errors... i would need to get
behind the complier and before the code actually runs. I don't want it to bump
up errors but rather just "mark" the code, in a manner similar to code
highlighting but not at the character/word level but at language level. "
The AST-Interpreter part: It seems we can do this with the help of the
AST, which has a certain implementation that requires a precise pattern of
interaction, and it's called the "visitor pattern". I also received a bump in
the direction of "Moose and friends (Roasal, PetitParser, .. )" which might
shed a little more light on the subject.
"You would need to write something like this (a visitor) or use the AST
interpreter (which
is just a fancy visitor)."
" Execute (Point>>#x) parseTree explore
in the Workspace to see a little of AST's power of going into classes and check
out below for a more detailed information
(Point>>#x) "==> (Point>>#x "a CompiledMethod(880017408)")"
#aSymbol is just a singletone version of the string "aSymbol"; In what to
classes concerns it is used as a unique identifier in the method dictionary.
The rest is just syntax ">>" is the selector(s) (method(s)) accessor, it will
retrieve the keyed selector (in this case #x which again is unique in the
class) value, which is a CompiledMethod(atSomeAddress).
Now you can also get the contents as a string if you want to parse it yourself
(compare to (Point>>#x) parseTree ):
(Point>>#x) definition "==> 'x
"Answer the x coordinate."
^x'"
Which is nothing more than the contents of the selector #x. I suggest, if you
want to get a "personalized" version of the parse tree, to try PetitParser,
there are many examples and even a Smalltalk80 parser in there."
PS. I will try to build a wiki to host this on a server so we can have a
central reference. Right now i will have to keep things in sync by hand.
PPS. I will try to keep a reference of who said what so that we can see ideas
from multiple people merging to a coherent solution.
Pe 28.01.2013, la 18:09, dcorking [via Smalltalk]
<[email protected]> a scris:
> A member of the AST-Interpreter[1] team posted a very interesting
> answer on Stack Overflow.[2]
>
> 1 - http://smalltalkhub.com/#!/~dh83/ast-interpreter
> 2 -
> http://stackoverflow.com/questions/14520133/programmatically-get-the-execution-order-of-objects-inside-a-method
>
> Have fun! David
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