Re: Formatted IO - Fortran style or similar.

[Adam Beneschan <adam@irvine.com>]

On Tuesday, July 31, 2012 8:12:37 AM UTC-7, (unknown) wrote:
> On Tue, 31 Jul 2012, Jacob Sparre Andersen wrote:
> 
> 
> 
> > How would you handle translatable user visible strings - such as
> > "Parsing '${file_name}' failed on line ${line_number}." (where "${...}"
> > identifies parameter substitutions) - in Ada?
> 
> Why do you need to *substitute* the parameters in the string at all? 
> 
> Without substitution, the following seems to work fine:

It's not a question of what anyone "needs" or what "works".  Yes, this works, but I can understand why, for some people, it makes things more readable to have the string that represents what the output is going to look like all in once nice place, rather than split up into fragments with expressions in between.  I find that sometimes doing it that way is a bit more readable, although I don't have a strong preference.

In addition, having a "format" specified as a single entity, with something to indicate where other values will be substituted, makes it easier and cleaner to select between different formats--say you have a table of formats where each format pertains to a different error message but many of them have the same types of information substituted in, or a table where each format represents the same message but in a different language.  Representing a format as a string constant with some special characters in it isn't the only way to do this, but it's an easy way that is readable and produces good results if the substitution syntax is simple enough.

                       -- Adam
 


>   Ada.Text_IO.Put_Line("Parsing "         & File_Name &  
>                        " failed on line " & To_String(Line_Number) & 
>                        ".");
>
> Of course, you still have to write your  
> 
>   function To_String(Line_Number: Line_Number_Type) return String; 
> 
> ... or you just use Line_Number'Image.