[M3devel] question on File.Status.size

[Tony Hosking]

Indeed, I wonder if it should be Long.T instead of LONGCARD, because I am uneasy with the assumption that the representation might not change.
(I can imagine a world where there is no LONGINT, and in which Long.T has some different representation than LONGINT.)
Now, on the other hand, POSIX specifies file sizes to be off_t, which is signed, whereas Long.T is meant to be thought of as unsigned.

So, should M3 adopt the POSIX spec that a file size is a signed value?  In which case I suppose LONGCARD makes sense.

On Sep 30, 2013, at 9:49 AM, "Coleburn, Randy" <rcolebur at SCIRES.COM> wrote:

> I haven't looked at the various underlying implementations of File.T but have they all been adjusted to deal with FS.Status.size now being a LONGCARD while the internal buffers are limited to arrays whose length can be no more than INTEGER?
> 
> If so, then I guess I need to adjust my code to deal with bigger files (even though my code won't actually use bigger files). 
> 
> I'm not complaining. I just want to make sure this interface change has been well thought out and implemented and is going to persist before I embark on changes to code that has been in production for years. 
> 
> Thanks,
> Randy Coleburn
> 
> Sent from my iPhone
> 
> On Sep 30, 2013, at 12:48 AM, "Jay K" <jay.krell at cornell.edu> wrote:
> 
>>  > NUMBER(array) to yield a LONGCARD
>> 
>>   This can't be.
>>   Arrays are in-memory data structures. 
>>   INTEGER/CARDINAL are an appropriate type
>>   to hold the size of something fits in memory/address-space.
>>   INTEGER is like C's ptrdiff_t. 
>>   CARDINAL is kind of like C's size_t, except it is half range. 
>>   Word.T is kind of like C's size_t, except it has no convenient in-fix operators. 
>> 
>> 
>>   Files commonly do not fit in memory/address-space. 
>>   So they arguably should have their size stored 
>>   in a larger type.
>> 
>> 
>>  I think there is no easy answer here.
>> 
>> 
>>  I would be ok with:
>>    - put it back to INTEGER/CARDINAL 
>>    - expose another way new way to get a LONGCARD 
>>  
>> 
>>  - Jay
>> 
>> 
>> 
>> 
>> From: rcolebur at SCIRES.COM
>> To: m3devel at elegosoft.com
>> Date: Sun, 29 Sep 2013 22:59:35 +0000
>> Subject: [M3devel] question on File.Status.size
>> 
>> I've been trying to rebuild all my developed software using my newly rebuilt cm3 from the HEAD branch.
>> 
>> I've run into some new build errors and have a question.
>> 
>> It seems the type of File.Status.size has been changed to LONGCARD.
>> 
>> I have some code that now fails to build because of this change.
>> 
>> I suppose this interface change is an attempt to better deal with files whose size in bytes is larger than MAX(CARDINAL).
>> 
>> So, for example:
>>    fs := FS.Status(file);
>>    INC(numBytes, fs.size);
>> no longer works if numBytes is defined as a CARDINAL.  Of course, I can change its type to be LONGCARD, but there will be a ripple effect throughout the code.
>> 
>> Has the language definition also been updated to allow NUMBER(array) to yield a LONGCARD ?
>> (Interface File uses open arrays)
>> 
>> In my old language definition, it says that:
>> An open array type declaration has the form: 
>>     TYPE T = ARRAY OF Element
>> where Element is any type. The values of T are arrays whose element type is Element and whose length is arbitrary. The index type of an open array is the INTEGER subrange [0..n-1], where n is the length of the array.
>> In the past NUMBER(x) always yielded a CARDINAL, not a LONGCARD.  So, if this has changed, I'll need to do some more updates across my code base.
>> 
>> How does one know in advance if NUMBER(x) is going to yield a CARDINAL or a LONGCARD value, esp. for open arrays?
>> 
>> Thanks,
>> Randy Coleburn
>> 

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