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digitalmars.D.learn - string object won't compile

reply askjfbd <icadraic9 gmail.com> writes:
Someone please tell me how, for I am a newbie and don't know any 
solutions even to this very simple problem. As I learned dlang 
using the Dlang tour page, I stuck at the alias & Strings page. I 
have tried to compile the following simple code many times but 
still get the same error both from dmd and gdc. They both say that
<----------------------------------------------------
string.d:9:9: error: module string is used as a type
   string str = "This is a test.";
---------------------------------------------------->
whenever I tried compiling this code below
<------------------------------------------
import std.stdio;
import std.string;

void main()
{
     //alias string = immutable(char)[];
     string str = "This is a test.";
}
------------------------------------------->
However, when I uncomment the alias~ line above,
both dmd and gdc can compile the code. I thought
that the string object is already defined in the
package or somewhere beforehand, but am I wrong?
Mar 05 2018
next sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Monday, 5 March 2018 at 23:34:50 UTC, askjfbd wrote:

 string.d


The problem is you named the file string.d and didn't give a 
`module xxxxx;` statement in the code, so the compiler assumed 
the module is named after the file.... and thus introduced a 
local name `string` referring to the module, overriding the built 
in one.

You can still refer to the built in one by saying `.string foo = 
"bar";` - yes, the leading dot, which tells it to use the global 
instead of local name.

Or by putting `module mytest.string;` at the top, so the module 
has a two-part name (I recommend this in all cases anyway btw, it 
is the best way to avoid conflicts as you import more modules).

Or just renaming the file from string.d to 
almost_anything_else.d, which will also avoid the local name 
override.
Mar 05 2018
parent askjfbd <icadraic9 gmail.com> writes:
On Monday, 5 March 2018 at 23:42:59 UTC, Adam D. Ruppe wrote:

 On Monday, 5 March 2018 at 23:34:50 UTC, askjfbd wrote:

 string.d


 The problem is you named the file string.d and didn't give a 
 `module xxxxx;` statement in the code, so the compiler assumed 
 the module is named after the file.... and thus introduced a 
 local name `string` referring to the module, overriding the 
 built in one.

 You can still refer to the built in one by saying `.string foo 
 = "bar";` - yes, the leading dot, which tells it to use the 
 global instead of local name.

 Or by putting `module mytest.string;` at the top, so the module 
 has a two-part name (I recommend this in all cases anyway btw, 
 it is the best way to avoid conflicts as you import more 
 modules).

 Or just renaming the file from string.d to 
 almost_anything_else.d, which will also avoid the local name 
 override.


Thanks for the precise advice. How foolish I was and how quickly 
you gave me the answer! I'll have to learn a lot more about D and 
more about modules. Since C and common lisp, which I have learned 
so far, have almost nothing to do with name conflicts, I couldn't 
imagine that I was still wrong. :) Thank you.
Mar 05 2018
prev sibling parent reply psychoticRabbit <meagain meagain.com> writes:
On Monday, 5 March 2018 at 23:34:50 UTC, askjfbd wrote:

 Someone please tell me how, for I am a newbie and don't know 
 any solutions even to this very simple problem. As I learned 
 dlang using the Dlang tour page, I stuck at the alias & Strings 
 page. I have tried to compile the following simple code many 
 times but still get the same error both from dmd and gdc. They 
 both say that...


This is mistake I made too, when i began using D.

I quickly got into the habit of putting

module test;

at the beginning of every file I create, unless I determine a 
better module name.

Actually, I wrote my own IDE, so it does that for me whenever I 
select a new D file.

Personally, I think that is one of the first things newcomers 
need to learn about - modules.

-------------
"Modules have a one-to-one correspondence with source files. The 
module name is, by default, the file name with the path and 
extension stripped off, and can be set explicitly with the module 
declaration."

"Modules automatically provide a namespace scope for their 
contents."

https://dlang.org/spec/module.html

------------
Mar 05 2018
parent askjfbd <icadraic9 gmail.com> writes:
On Tuesday, 6 March 2018 at 00:18:14 UTC, psychoticRabbit wrote:

 On Monday, 5 March 2018 at 23:34:50 UTC, askjfbd wrote:

 Someone please tell me how, for I am a newbie and don't know 
 any solutions even to this very simple problem. As I learned 
 dlang using the Dlang tour page, I stuck at the alias & 
 Strings page. I have tried to compile the following simple 
 code many times but still get the same error both from dmd and 
 gdc. They both say that...


 This is mistake I made too, when i began using D.

 I quickly got into the habit of putting

 module test;

 at the beginning of every file I create, unless I determine a 
 better module name.

 Actually, I wrote my own IDE, so it does that for me whenever I 
 select a new D file.

 Personally, I think that is one of the first things newcomers 
 need to learn about - modules.

 -------------
 "Modules have a one-to-one correspondence with source files. 
 The module name is, by default, the file name with the path and 
 extension stripped off, and can be set explicitly with the 
 module declaration."

 "Modules automatically provide a namespace scope for their 
 contents."

 https://dlang.org/spec/module.html

 ------------


Thank you. I will learn about modules from now on. I thought I 
was right until you two replied to me. ;) Can you make your own 
IDE? That's great! If it were OpenSource, I would gladly download 
it for myself to avoid this sort of annoying experience. Thanks.
Mar 05 2018