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digitalmars.D.learn - defining in a module symbols for export

reply spir <denis.spir gmail.com> writes:
Hello,

Let us say I have a parsing library. Now, I want to define parsers in stand=
-alone modules -- for code structuration and reusability. Then, import them=
 from apps that need them.
Is there another way than defining the parser (=3D=3D list of patterns) at =
the module's top-level. I have nothing against this, since the module is de=
dicated to this anyway -- but dmd refuses.
More generally, I find myself unable to define structured objects at a modu=
les's top level. for instancz:

=3D=3D=3D mod.d =3D=3D
import std.stdio;

struct S {
    int i;
    void speak() {writeln("i: ",this.i);}
}
=3D=3D=3D __trials__.d =3D=3D=3D
import mod;

auto s =3D S();
s.speak();
s.i =3D 1;
writeln(s.i);

void main () {
}

=3D=3D=3D compilation =3D=3D=3D
__trials__.d(19): no identifier for declarator s.speak
__trials__.d(20): no identifier for declarator s.i
__trials__.d(21): found '.' when expecting ')'
__trials__.d(21): semicolon expected, not 'i'
__trials__.d(21): no identifier for declarator i
__trials__.d(21): semicolon expected, not ')'
__trials__.d(21): Declaration expected, not ')'

Why does dmd refuse? If I put the code in a function, I can compile, link, =
and run it. But this does not match my use case: I need to export symbols (=
patterns) defined there; so, i guess, they must be defined at the top of th=
e module. Is there another solution?

I take the opportunity to ask whether it is possible to define which symbol=
s are to be _ex_ported.


Denis
-- -- -- -- -- -- --
vit esse estrany =E2=98=A3

spir.wikidot.com
Nov 22 2010
next sibling parent bearophile <bearophileHUGS lycos.com> writes:
spir:

 More generally, I find myself unable to define structured objects at a
modules's top level. for instancz:

I suggest to declare global variables and then initialize them in a "static this() {...}". But generally I suggest you to minimize the number of global variables. Bye, bearophile
Nov 22 2010
prev sibling next sibling parent =?UTF-8?B?UGVsbGUgTcOlbnNzb24=?= <pelle.mansson gmail.com> writes:
On 11/22/2010 08:18 PM, spir wrote:
 Hello,

 Let us say I have a parsing library. Now, I want to define parsers in
stand-alone modules -- for code structuration and reusability. Then, import
them from apps that need them.
 Is there another way than defining the parser (== list of patterns) at the
module's top-level. I have nothing against this, since the module is dedicated
to this anyway -- but dmd refuses.
 More generally, I find myself unable to define structured objects at a
modules's top level. for instancz:

 === mod.d ==
 import std.stdio;

 struct S {
      int i;
      void speak() {writeln("i: ",this.i);}
 }
 === __trials__.d ===
 import mod;

 auto s = S();
 s.speak();
 s.i = 1;
 writeln(s.i);

 void main () {
 }

 === compilation ===
 __trials__.d(19): no identifier for declarator s.speak
 __trials__.d(20): no identifier for declarator s.i
 __trials__.d(21): found '.' when expecting ')'
 __trials__.d(21): semicolon expected, not 'i'
 __trials__.d(21): no identifier for declarator i
 __trials__.d(21): semicolon expected, not ')'
 __trials__.d(21): Declaration expected, not ')'

 Why does dmd refuse? If I put the code in a function, I can compile, link, and
run it. But this does not match my use case: I need to export symbols
(patterns) defined there; so, i guess, they must be defined at the top of the
module. Is there another solution?

 I take the opportunity to ask whether it is possible to define which symbols
are to be _ex_ported.


 Denis
 -- -- -- -- -- -- --
 vit esse estrany ☣

 spir.wikidot.com

To initialize at runtime: S s; static this() { s.i = 1; } to initialize at compile time: S getS() { S s; s.i = 1; return s; } S s = getS(); Use public/private to control which symbols are availible. Unfortunately, this doesn't really work at the moment :-)
Nov 22 2010
prev sibling next sibling parent spir <denis.spir gmail.com> writes:
On Mon, 22 Nov 2010 15:11:29 -0500
bearophile <bearophileHUGS lycos.com> wrote:

 spir:
=20
 More generally, I find myself unable to define structured objects at a =


=20
 I suggest to declare global variables and then initialize them in a "stat=

bal variables.
=20
 Bye,
 bearophile

Yes, I would generally agree (I normally have about nothing at module tople= vel), but then how can they be exported? A parser module is precisely here = to define symbols for export... How do you guys write that? denis -- -- -- -- -- -- -- vit esse estrany =E2=98=A3 spir.wikidot.com
Nov 22 2010
prev sibling next sibling parent Jesse Phillips <jessekphillips+D gmail.com> writes:
spir Wrote:


 === mod.d ==
 import std.stdio;
 
 struct S {
     int i;
     void speak() {writeln("i: ",this.i);}
 }
 === __trials__.d ===
 import mod;
 
 auto s = S();
 s.speak();
 s.i = 1;
 writeln(s.i);
 
 void main () {
 }

Others have answered how to initialize variables, but haven't explained the compilation error. A simple example of what you are doing wrong is: import std.stdio; writeln("foo"); void main () { } How are you to execute writeln()? You probably wouldn't try this under normal conditions, but is what you are trying to do. You can place it in a static this constructor: import std.stdio; static this() { writeln("foo"); } void main () { } Note you can move the calls into main and it compiles fine: void main () { s.speak(); s.i = 1; writeln(s.i); }
Nov 22 2010
prev sibling next sibling parent spir <denis.spir gmail.com> writes:
On Mon, 22 Nov 2010 22:17:46 +0100
Pelle M=C3=A5nsson <pelle.mansson gmail.com> wrote:

 On 11/22/2010 08:18 PM, spir wrote:
 Hello,

 Let us say I have a parsing library. Now, I want to define parsers in s=


them from apps that need them.
 Is there another way than defining the parser (=3D=3D list of patterns)=


s dedicated to this anyway -- but dmd refuses.
 More generally, I find myself unable to define structured objects at a =


 =3D=3D=3D mod.d =3D=3D
 import std.stdio;

 struct S {
      int i;
      void speak() {writeln("i: ",this.i);}
 }
 =3D=3D=3D __trials__.d =3D=3D=3D
 import mod;

 auto s =3D S();
 s.speak();
 s.i =3D 1;
 writeln(s.i);

 void main () {
 }

 =3D=3D=3D compilation =3D=3D=3D
 __trials__.d(19): no identifier for declarator s.speak
 __trials__.d(20): no identifier for declarator s.i
 __trials__.d(21): found '.' when expecting ')'
 __trials__.d(21): semicolon expected, not 'i'
 __trials__.d(21): no identifier for declarator i
 __trials__.d(21): semicolon expected, not ')'
 __trials__.d(21): Declaration expected, not ')'

 Why does dmd refuse? If I put the code in a function, I can compile, li=


ls (patterns) defined there; so, i guess, they must be defined at the top o= f the module. Is there another solution?
 I take the opportunity to ask whether it is possible to define which sy=


 Denis
 -- -- -- -- -- -- --
 vit esse estrany =E2=98=A3

 spir.wikidot.com

To initialize at runtime: =20 S s; static this() { s.i =3D 1; } =20 to initialize at compile time: =20 S getS() { S s; s.i =3D 1; return s; } S s =3D getS(); =20 Use public/private to control which symbols are availible.=20 Unfortunately, this doesn't really work at the moment :-)

Thank you very much! Unfortunately, a parser is typically a bunch a definitions. I cannot expect= the user (first, myself) to write a func for every little setting needed. I could write setters on classes that require the user to set attributes, b= ut as shown in the example, method calls are also refused. Where is the issue, actually? Denis -- -- -- -- -- -- -- vit esse estrany =E2=98=A3 spir.wikidot.com
Nov 23 2010
prev sibling parent spir <denis.spir gmail.com> writes:
On Mon, 22 Nov 2010 16:20:07 -0500
Jesse Phillips <jessekphillips+D gmail.com> wrote:

 spir Wrote:
=20
=20
 =3D=3D=3D mod.d =3D=3D
 import std.stdio;
=20
 struct S {
     int i;
     void speak() {writeln("i: ",this.i);}
 }
 =3D=3D=3D __trials__.d =3D=3D=3D
 import mod;
=20
 auto s =3D S();
 s.speak();
 s.i =3D 1;
 writeln(s.i);
=20
 void main () {
 }

Others have answered how to initialize variables, but haven't explained t=

=20
 import std.stdio;
=20
 writeln("foo");
=20
 void main () {
 }
=20
 How are you to execute writeln()? You probably wouldn't try this under no=

atic this constructor:
=20
 import std.stdio;
=20
 static this() { writeln("foo"); }
=20
 void main () {
 }
=20
 Note you can move the calls into main and it compiles fine:
=20
 void main () {
 s.speak();
 s.i =3D 1;
 writeln(s.i);
 }
=20

Right. Seems I may put the whole parser definition into static this(). I'll= try it. Will work if symbols defined in there are available for export. Denis -- -- -- -- -- -- -- vit esse estrany =E2=98=A3 spir.wikidot.com
Nov 23 2010