error recovery

error recovery

[Noam Kloos]

Hello,

I have written a small program and I don't like the exeception
handlling;

Normally when Name_Error my program creates the missing file.
But after exception has been raised the program ends.
So my way to do it was; when Name_Error; Create File, call the program
itself.

I get a possible infinite recursion warning, but wont get storage
error while the action can occur only once.

This is my way to do error recovery (something that belongs to OOPS)
http://www.noam.nl/ada95/action.zip

Is there a better way to realise error recovery in Ada?
Noam.

Re: error recovery

[Staffan Dittmer]

In article <3afbe7e2.191078067@news.nl.uu.net>,
	serious@clerk.com (Noam Kloos) writes:

> But after exception has been raised the program ends.
> So my way to do it was; when Name_Error; Create File, call the program
> itself.
> 
> Is there a better way to realise error recovery in Ada?
> Noam.
>
 
Guess you should check the ARM about the range(?) of exceptions.
The solution to your problem is adding a new block inside your main
program,  or a procedure,  that handles the exception locally without 
interrupting the rest of your program.

In your case a block solution would be

open_file_block:
 begin
    Open(File_Log,Append_File,Log_File_Name);
   exception
   when Name_Error => Create(File_Log,In_File,Log_File_Name);
end open_file_block;

then do all the putting things....

/ Staffan

Re: error recovery

[Ehud Lamm]

What you do is put the code that may raise an exception inside a blok, and
since you want to try again, put the block inside a loop.

This is a standard idiom, and you can see how it is used by checking the
code examples on Adapower (http://www.adapower.com/lang/safeio.html is an
example of mine that does almost nothing except catch exceptions :-) check
the "get" routine).


--
Ehud Lamm   mslamm@mscc.huji.ac.il
http://purl.oclc.org/NET/ehudlamm <==  Me!