Advanced Macros && Preprocessors

[Let_Me_Be]

Hi all,
I'm developing a small defensive programming toolkit for my own
projects. So, here are my questions.

1) Is it possible to move from something like this: SAFECALL(foo() to
__safecall foo();

2) I need to auto-add code to every method of particular class
safeclass MyClass
{
public:
void foo();
}

void MyClass::foo() {}

will modify the foo implementation - add some lines of code on the end
of the method

3) even more advanced stuff, is it possible to modify the preprocessor
(or add my own preprocessor)? I need to parse something like this.
__precheck minutes >= 0 && minutes < 60 #Checking minutes variable for
valid time information
void foo(int minutes){}
__postcheck minutes % 10 == 0 #Checking if minutes have been rounded to
10 minutes intervals
I need also the text behind #

 

[Vladimir Oka]

Let_Me_Be opined:

Hi all,
I'm developing a small defensive programming toolkit for my own
projects. So, here are my questions.

1) Is it possible to move from something like this: SAFECALL(foo()
to __safecall foo();

2) I need to auto-add code to every method of particular class
safeclass MyClass
{
public:
void foo();
}

void MyClass::foo() {}

Are you sure you don't want comp.lang.c++?

will modify the foo implementation - add some lines of code on the
end of the method

3) even more advanced stuff, is it possible to modify the
preprocessor (or add my own preprocessor)? I need to parse something
like this. __precheck minutes >= 0 && minutes < 60 #Checking minutes
variable for valid time information
void foo(int minutes){}
__postcheck minutes % 10 == 0 #Checking if minutes have been rounded
to 10 minutes intervals
I need also the text behind #

--
A father doesn't destroy his children.
-- Lt. Carolyn Palamas, "Who Mourns for Adonais?",
stardate 3468.1.

<http://clc-wiki.net/wiki/Introduction_to_comp.lang.c>

 

[Let_Me_Be]

Are you sure you don't want comp.lang.c++?
Nope, this was just an example, my toolkit should work in both c/c++.

 

[Ian Collins]

Hi all,
I'm developing a small defensive programming toolkit for my own
projects. So, here are my questions.

1) Is it possible to move from something like this: SAFECALL(foo() to
__safecall foo();

2) I need to auto-add code to every method of particular class
safeclass MyClass
{
public:
void foo();
}

void MyClass::foo() {}

Wrong group, if you look carefully, you will spot the absence of "++" at
the end of this group's name.

 

[Vladimir Oka]

Let_Me_Be opined:

Nope, this was just an example, my toolkit should work in both c/c++.

Presumably then, you posted the same question to comp.lang.c++, with an
example in C?

In c.l.c you can only get the C perspective. Whether that's going to be
of any use in C++ is not something to be found (or discussed) here.

Also, do not snip attribution lines (the ones who tell us who said
what), and leave enough context so that your post can be grasped in
isolation. The above worked only because I remembered it was me, and
what I replied to. Read the link in my sig.

--
In Pocatello, Idaho, a law passed in 1912 provided that "The carrying
of concealed weapons is forbidden, unless same are exhibited to public
view."

<http://clc-wiki.net/wiki/Introduction_to_comp.lang.c>

 

[Eric Sosman]

Nope, this was just an example, my toolkit should work in both c/c++.

Speaking for myself, I found the examples did not cast
much light on your intentions. What are you trying to do?

The first question was

> 1) Is it possible to move from something like this: SAFECALL(foo()
> to
> __safecall foo();

.... and it's not at all clear how "like" the actual "something"
would be, nor what sort of "motion" you desire. The second was

> 2) I need to auto-add code to every method of particular class

.... and I'm unable to imagine how this could have any "image" in
C. All C functions (taking "function" as a translation of "method")
have the same status, as it were: they do not belong to any larger
groupings like "class" or "package," so I can see no way to decide
which functions require manipulation and which should be left alone.
This part of your toolkit needs more explanation -- or, as Vladimir
suggests, you need to take your question elsewhere.

The third example (see up-thread) looks like gibberish. You're
evidently trying to introduce some sort of assertion or error-check,
but you're doing so with a syntax that doesn't look anything at all
like C. Again, either your question needs elaboration or it needs
relocation.

One of the most valuable skills a programmer can hone is the
ability to ask good questions, questions that provide the necessary
information and state clearly what is wanted. You'll forgive me,
I hope, my opinion that you need practice in this skill.

 

[Let_Me_Be]

The first question was

... and it's not at all clear how "like" the actual "something"
would be, nor what sort of "motion" you desire. The second was

Currently i'm using SAFECALL macro, the syntax is SAFECALL(something),
well, it does work, but much nicer would be __safecall something.

... and I'm unable to imagine how this could have any "image" in
C. All C functions (taking "function" as a translation of "method")
have the same status, as it were: they do not belong to any larger
groupings like "class" or "package," so I can see no way to decide
which functions require manipulation and which should be left alone.
This part of your toolkit needs more explanation -- or, as Vladimir
suggests, you need to take your question elsewhere.

Ok, i will try to talk about this in the c++ group.

The third example (see up-thread) looks like gibberish. You're
evidently trying to introduce some sort of assertion or error-check,
but you're doing so with a syntax that doesn't look anything at all
like C. Again, either your question needs elaboration or it needs
relocation.

Problem - visualy divide main code and assertions. I'm acctualy trying
to implement functionality similar to Eiffel.

The syntax doesn't look like C because it isn't C Well, that's why
this thread is called Advanced Macros && Preprocessors. The syntax
actualy should look something like this MACRO-HEADER BOOLEAN-EXP
COMMENT (the comment should appear in the error message), or even
better
_start of check block
exp comment
exp comment
_end of check block

Idealy the block should appear after the function header, before the
main code.

 

[Eric Sosman]

Let_Me_Be wrote On 04/28/06 09:21,:

Currently i'm using SAFECALL macro, the syntax is SAFECALL(something),
well, it does work, but much nicer would be __safecall something.

Whether you can do this depends on what SAFECALL expands
to. If SAFECALL(x) produces bunch_of_stuff x, then you can
simply define a __safecall macro producing bunch_of_stuff.
If SAFECALL(x) does something more complicated, it cannot be
replaced by an object-like __safecall macro whose expansion
does not itself involve x.

By the way, using two underscores at the start of the
macro name is begging for trouble. Such names "are always
reserved for any use" (7.1.3/1), which means "if you use
them in your program and something goes wrong, it's your
fault and no one else's."

The syntax doesn't look like C because it isn't C [...]

So why ask about it in a C forum? Wouldn't alt.woodworking
be equally appropriate?

 

[Ben Pfaff]

1) Is it possible to move from something like this: SAFECALL(foo() to
__safecall foo();

This macro will make that literal substitution, although I can't
see how it's useful:
#define SAFECALL(arg) __safecall arg

[...C++ question omitted...]

3) even more advanced stuff, is it possible to modify the preprocessor
(or add my own preprocessor)? I need to parse something like
this. [...]

You can always write your own preprocessor to translate whatever
you like into C. If you use a "make" or similarly powerful build
system, it's not any hard to build such a project than it is to
build an ordinary C project.

 

[Thad Smith]

Currently i'm using SAFECALL macro, the syntax is SAFECALL(something),
well, it does work, but much nicer would be __safecall something.

which doesn't address the issue raised above. "It works" is not a
sufficient description.

One of the options you mentioned earlier is to write your own
preprocessor. If you do that, you can use any syntax you like, but if
you need full C and C++ parsing, the job will be much bigger.

I guess you need to write your own. There are probably tools available
to help parse your target language.