www.digitalmars.com         C & C++   DMDScript  

D - GC & module constructor

reply "Lloyd Dupont" <lloyd galador.net> writes:
I have 2 question:

1./ about Module
---------------------
I try

extern (C) char* getenv(char*);
char[] tostring(char* cstring)
{
    int n = strlen(cstring);
    return cstring[0 .. n];
}
char[] PATH = tostring(getenv("PATH"));

and it keep failing dmd outputting:

 f.d(11): non-constant expression tostring(getenv("PATH"))


I also tried (property)

char[] PATH() { return tostring(getenv("PATH")); }
....
and later printf(PATH ~ " It worked!\n");
but it doesn't work either.
how could I initialise my module variable ??

2./ about Garbage Collection:
------------------------------------
I am a bit puzzled in you "wc" example you don't initialiase gc at all.. is
it garbage collected ?
I wonder if garbage collection is enabled by default or not, as your (other)
example "D for win32" you explicitly initialise it...

should I initialise explicitly or not ?


3./ yes :-D
-------------
why don't you link directly with DLL as gcc do ?
I found it's a nice feature and it ease life so much...
Nov 08 2002
parent reply "Walter" <walter digitalmars.com> writes:
"Lloyd Dupont" <lloyd galador.net> wrote in message
news:aqi0ur$19h$1 digitaldaemon.com...

 I have 2 question:

 1./ about Module
 ---------------------
 I try

 extern (C) char* getenv(char*);
 char[] tostring(char* cstring)
 {
     int n = strlen(cstring);
     return cstring[0 .. n];
 }
 char[] PATH = tostring(getenv("PATH"));

 and it keep failing dmd outputting:

 f.d(11): non-constant expression tostring(getenv("PATH"))




No dynamic initializers, try instead:
    char[] PATH;
    PATH = tostring ...


 I also tried (property)

 char[] PATH() { return tostring(getenv("PATH")); }
 ....
 and later printf(PATH ~ " It worked!\n");
 but it doesn't work either.
 how could I initialise my module variable ??

 2./ about Garbage Collection:
 ------------------------------------
 I am a bit puzzled in you "wc" example you don't initialiase gc at all..


is

 it garbage collected ?
 I wonder if garbage collection is enabled by default or not, as your


(other)

 example "D for win32" you explicitly initialise it...

 should I initialise explicitly or not ?


The runtime library automatically initializes the GC for you.


 3./ yes :-D
 -------------
 why don't you link directly with DLL as gcc do ?
 I found it's a nice feature and it ease life so much...


I don't know what you mean here - what DLL?
Nov 08 2002
parent reply "Lloyd Dupont" <lloyd galador.net> writes:
 No dynamic initializers, try instead:
     char[] PATH;
     PATH = tostring ...


I meant, what about that

import string;

extern (C) char* getenv(char*);
char[] tostring(char* cstring)
{
    int n = strlen(cstring);
    return cstring[0 .. n];
}

char[] PATH;
PATH = tostring(getenv("PATH"));

// dmd f.d -o f.exe && f
void main (char[][] args)
{
    printf(PATH ~ " -- HEHE --");
}

this doesn't compile.
of course I could imagine PATH being a function (PATH()). using a lazy
value.
but I wonder if there is away to have an init() function, called only once
by module,
which could initialiaze my variables....


 The runtime library automatically initializes the GC for you.


ah, cool !...
so why do you initialize it in you "D for Win32" examples ?
is it because the programs start in WinMain, in which case the runtime is
not initialized ?
(and idem in DllMain for DLL ?)


 3./ yes :-D
 -------------
 why don't you link directly with DLL as gcc do ?
 I found it's a nice feature and it ease life so much...


 I don't know what you mean here - what DLL?


well here is an example

#include <stdio.h>
#define DLLOBJECT __declspec(dllexport)

DLLOBJECT void writeln(char* s)
{
     printf("%s\n", s);
}

compile with "gcc -shared -o dll.dll dll.c"

__declspec(dllimport) void writeln(char* s);

main()
{
    writeln("Hello");
}

compile with "gcc -o a.exe a.c dll.dll"

you see, I link directly with the DLL, no def file, no lib file, only 1
step, simple..
Nov 09 2002
parent reply Patrick Down <pat codemoon.com> writes:
"Lloyd Dupont" <lloyd galador.net> wrote in
news:aqiioa$jk3$1 digitaldaemon.com: 



 but I wonder if there is away to have an init() function, called only
 once by module,
 which could initialiaze my variables....


http://www.digitalmars.com/d/module.html

Static module constuctors and destructors

char[] PATH;

static this()
{
    	PATH = tostring(getenv("PATH"));
}
Nov 09 2002
next sibling parent reply "Sean L. Palmer" <seanpalmer directvinternet.com> writes:
But I'd rather be able to do it in the initializer.  Static variable
initializers should effectively be automatically transferred to the module's
static ctor.  Same as member variable initializers effectively occurring
when the ctor(s) are called.

I figure just about anything you can do with assignment you should be able
to do in an initializer.  Why not?  It's convenient.

Sean

"Patrick Down" <pat codemoon.com> wrote in message
news:Xns92C15DCA09ED9patcodemooncom 63.105.9.61...

 "Lloyd Dupont" <lloyd galador.net> wrote in
 news:aqiioa$jk3$1 digitaldaemon.com:



 but I wonder if there is away to have an init() function, called only
 once by module,
 which could initialiaze my variables....


 http://www.digitalmars.com/d/module.html

 Static module constuctors and destructors

 char[] PATH;

 static this()
 {
     PATH = tostring(getenv("PATH"));
 }
Nov 09 2002
parent "Walter" <walter digitalmars.com> writes:
"Sean L. Palmer" <seanpalmer directvinternet.com> wrote in message
news:aqjt49$28nr$1 digitaldaemon.com...

 But I'd rather be able to do it in the initializer.  Static variable
 initializers should effectively be automatically transferred to the


module's

 static ctor.  Same as member variable initializers effectively occurring
 when the ctor(s) are called.

 I figure just about anything you can do with assignment you should be able
 to do in an initializer.  Why not?  It's convenient.


It is convenient, but I wanted to be able to distinguish between what is
computed at runtime and what is at compile time. The way it is now makes it
pretty obvious.
Nov 13 2002
prev sibling parent "Lloyd Dupont" <lloyd galador.net> writes:
ha, oh, .. thanks..
I read that but didn't guess what was the static constructor,
thanks to outlined it with your example :-)

"Patrick Down" <pat codemoon.com> a écrit dans le message de news:
Xns92C15DCA09ED9patcodemooncom 63.105.9.61...

 "Lloyd Dupont" <lloyd galador.net> wrote in
 news:aqiioa$jk3$1 digitaldaemon.com:

 but I wonder if there is away to have an init() function, called only
 once by module,
 which could initialiaze my variables....


 http://www.digitalmars.com/d/module.html

 Static module constuctors and destructors

 char[] PATH;

 static this()
 {
     PATH = tostring(getenv("PATH"));
 }
Nov 09 2002