Do I have to create a dummy file to satisfy the compiler? ;)

[Curly]

I am iterating across a list of items, whose names are used to create files.

The compiler insists that I initialise the PLAIN_TEXT_FILE object before I enter the loop.

Does this mean that I have to create a dummy file pre-loop just to satisfy the compiler, or is there another way?

[Alexander Kogtenkov]

Would you share the code with the issue, please?

 

Alexander Kogtenkov

 

 

Суббота, 30 ноября 2019, 21:22 +03:00 от Curly <gimmean...@gmail.com>:
 

I am iterating across a list of items, whose names are used to create files.

 

The compiler insists that I initialise the PLAIN_TEXT_FILE object before I enter the loop.

 

Does this mean that I have to create a dummy file pre-loop just to satisfy the compiler, or is there another way?

 

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[Curly]

Hi Alexander,

I thought it self-explanatory, but when I came to put an example together for you, I realised it wasn't!

Here's the 'bad' code:

    ml_filename: STRING
    ml_output_file: PLAIN_TEXT_FILE

    make
        local
            division_list: ARRAY[STRING]

        do
            division_list := << "E0", "E1" >>


            ml_filename := ""
--          create ml_output_file.make_create_read_write ("C:\Dummy_file.csv")


            across division_list as division_entry
            loop
                ml_filename := "C:\Example\" + division_entry.item.out + "\real_file.csv"
                create ml_output_file.make_open_write (ml_filename)

                ml_output_file.close
            end -- division_list loop
        end -- make

This will only work as-is if you uncomment the dummy file creation.

I have now noticed, however, that if the file descriptors are made local instead of global it works as I intended.

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

On Saturday, 30 November 2019 20:33:44 UTC, Alexander Kogtenkov wrote:

Would you share the code with the issue, please?

 

Alexander Kogtenkov

 

 

Суббота, 30 ноября 2019, 21:22 +03:00 от Curly <gimmean...@gmail.com>:
 

I am iterating across a list of items, whose names are used to create files.

 

The compiler insists that I initialise the PLAIN_TEXT_FILE object before I enter the loop.

 

Does this mean that I have to create a dummy file pre-loop just to satisfy the compiler, or is there another way?

 

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[Bertrand Meyer]

ml_output_file is an attribute. Since it is declared as attached, every creation procedure has to make sure it is non-void on exit of the procedure (i.e. on start of the object’s life).

 

The loop could be executed zero times. In that case, without the commented-out line, the attribute would be void.

 

-- BM

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[Curly]

Thanks for the clarification, Bertrand.

Even though it's in the basics, I hadn't paid attention to attached and detachable. If I'd spotted that earlier it would have saved me a lot of trouble!

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