Re: Particular exceptions names

[kdevel via Digitalmars-d-learn]

On Wednesday, 27 July 2022 at 09:35:12 UTC, Ali Çehreli wrote:

The following program show an example as well as 'enforce', 
which I prefer over explicit if+throw+else:


Me too.


  enforce!MissingArguments(args.length == 42,
   format!"Too few arguments: 
%s"(args.length));


However, this particular form lowers the readability a lot. It is 
not the absence of arguments which is enforced but the length of 
the args array, i.e. the presence of the arguments. Therefore I 
prefer


   enforce (args.length == 42, new MissingArguments (...));

Re: Particular exceptions names

[kdevel via Digitalmars-d-learn]

On Tuesday, 26 July 2022 at 23:43:59 UTC, pascal111 wrote:

In next example code, it used user-made exception,



[...]



   try {
  if( b == 0 ) {
 throw new Exception("Cannot divide by zero!");
  } else {
 result = format("%s",a/b);
  }



[...]



void main () {
   int x = 50;
   int y = 0;


What about the case x = -2147483648, y = -1?

Re: Particular exceptions names

[pascal111 via Digitalmars-d-learn]

On Wednesday, 27 July 2022 at 09:35:12 UTC, Ali Çehreli wrote:

On 7/26/22 16:43, pascal111 wrote:
> [...]

I am not sure I understand you correctly because the program 
you show throws Exception, which is not user-made at all.


[...]


It seems an advanced topic. It'll take some more studying to 
understand this code.

Re: Particular exceptions names

[Ali Çehreli via Digitalmars-d-learn]

On 7/26/22 16:43, pascal111 wrote:
> In next example code, it used user-made exception,

I am not sure I understand you correctly because the program you show 
throws Exception, which is not user-made at all.


If you want to throw a particual exception that you define, you need to 
inherit that type from Exception.


The following program show an example as well as 'enforce', which I 
prefer over explicit if+throw+else:


import std.stdio;
import std.format;

class MissingArguments : Exception {
  this(string msg, string file = __FILE__, size_t line = __LINE__) {
super(msg, file, line);
  }
}

void main(string[] args) {
  // if (args.length != 42) {
  //   throw new MissingArguments(args.length);
  // }

  import std.exception : enforce;
  enforce!MissingArguments(args.length == 42,
   format!"Too few arguments: %s"(args.length));

  // Program continues here... (No 'else' needed.)
}

Ali

Re: Particular exceptions names

[frame via Digitalmars-d-learn]

On Tuesday, 26 July 2022 at 23:43:59 UTC, pascal111 wrote:
In next example code, it used user-made exception, but what if 
I'm looking for a particular exception? from where can I get 
particular exception to arise it?


There is no mechanism to find a particular exceptions in D. You 
have simple to know which exception can be thrown by studying the 
documentation or source code.


If you just want to give the user an information which exception 
was thrown in run time, use typeid:


```d
try { ... }
catch(Exception e) {
writefln("%s was thrown", typeid(e));
}
```

Particular exceptions names

[pascal111 via Digitalmars-d-learn]

In next example code, it used user-made exception, but what if 
I'm looking for a particular exception? from where can I get 
particular exception to arise it?



import std.stdio;
import std.string;

string division(int a, int b) {
   string result = "";

   try {
  if( b == 0 ) {
 throw new Exception("Cannot divide by zero!");
  } else {
 result = format("%s",a/b);
  }
   } catch (Exception e) {
  result = e.msg;
   }

   return result;
}

void main () {
   int x = 50;
   int y = 0;

   writeln(division(x, y));

   y = 10;
   writeln(division(x, y));
}

source site:
https://www.tutorialspoint.com/d_programming/d_programming_exception_handling.htm