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digitalmars.D.learn - TIL: statically initializing an Associative Array

reply Andy Valencia <dont spam.me> writes:
I had a set of default error messages to go with error code 
numbers, and did something along the lines of:

string[uint] error_text = [
     400: "A message",
     401: "A different message"
];

and got "expression .... is not a constant"

I eventually found this discussion:
     https://issues.dlang.org/show_bug.cgi?id=6238

I understand that it's problematic, but a message which makes it 
clearer that compile-time initialization of global AA's are not 
supported?  Because it cost me about a half hour trying to figure 
out what I was doing wrong.

(My workaround was to initialize the data structure once during 
app startup.)
May 06
next sibling parent reply matheus <matheus gmail.com> writes:
On Tuesday, 7 May 2024 at 00:10:27 UTC, Andy Valencia wrote:

 I had a set of default error messages to go with error code 
 numbers, and did something along the lines of:

 string[uint] error_text = [
     400: "A message",
     401: "A different message"
 ];

 and got "expression .... is not a constant"

 I eventually found this discussion:
     https://issues.dlang.org/show_bug.cgi?id=6238

 I understand that it's problematic, but a message which makes 
 it clearer that compile-time initialization of global AA's are 
 not supported?  Because it cost me about a half hour trying to 
 figure out what I was doing wrong.

 (My workaround was to initialize the data structure once during 
 app startup.)


Based on what I understood and that issue, I think it was fixed:

import std.stdio;

string[uint] aa1 = [1:"ABC",2:"DEF"];

void main(){
     auto aa2 = ['A':1,'B':2];

     writeln(aa1[1]);
     writeln(aa1[2]);
     writeln(aa2['A']);
     writeln(aa2['B']);
}

Prints:

ABC
DEF
1
2

Matheus.
May 06
parent matheus <matheus gmail.com> writes:
On Tuesday, 7 May 2024 at 01:02:04 UTC, matheus wrote:

 On Tuesday, 7 May 2024 at 00:10:27 UTC, Andy Valencia wrote:
 ...
 Based on what I understood and that issue, I think it was fixed:
 ...


By the way it works as immutable too.

Matheus.
May 06
prev sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On Tuesday, 7 May 2024 at 00:10:27 UTC, Andy Valencia wrote:

 I had a set of default error messages to go with error code 
 numbers, and did something along the lines of:

 string[uint] error_text = [
     400: "A message",
     401: "A different message"
 ];

 and got "expression .... is not a constant"

 I eventually found this discussion:
     https://issues.dlang.org/show_bug.cgi?id=6238

 I understand that it's problematic, but a message which makes 
 it clearer that compile-time initialization of global AA's are 
 not supported?  Because it cost me about a half hour trying to 
 figure out what I was doing wrong.


This error message was changed in 2.101.x (unsure which point 
release):

```
onlineapp.d(1): Error: static initializations of associative 
arrays is not allowed.
onlineapp.d(1):        associative arrays must be initialized at 
runtime: 
https://dlang.org/spec/hash-map.html#runtime_initialization
```


 (My workaround was to initialize the data structure once during 
 app startup.)


This was fixed [in 
2.106.0](https://dlang.org/changelog/2.106.0.html#dmd.static-assoc-array)

  please upgrade your compiler.

-Steve
May 06
parent Andy Valencia <dont spam.me> writes:
On Tuesday, 7 May 2024 at 01:14:24 UTC, Steven Schveighoffer 
wrote:

 On Tuesday, 7 May 2024 at 00:10:27 UTC, Andy Valencia wrote:

 I had a set of default error messages to go with error code 
 numbers, and did something along the lines of:

 string[uint] error_text = [
     400: "A message",
     401: "A different message"
 ];

 and got "expression .... is not a constant"


 ...
 This was fixed [in 
 2.106.0](https://dlang.org/changelog/2.106.0.html#dmd.static-assoc-array)

  please upgrade your compiler.


I'm using ldc2 from Debian stable; great news that it's fixed as 
of late 2023.  I'll probably live with my workaround, but it's 
good to know that it's a bug which has been resolved.

Thank you!
Andy
May 06