Re: Table of pointers question

[Rob Solomon <usenet@drrob1-noreply.com>]

>> > I am working my way thru Ada As A Second Language by Norman Cohen (c)
>> > 1996
>>
>> > This confuses me.
>>
>> > It is a simple sorting routine that swaps pointers rather than the
>> > data. �Note that the variables are more like Modula-2 syntax as I am
>> > very comfortable with that. �And it is easier to type.
>>
>> Has something gone wrong when (I'm guessing here) the
>> program was rewritten for Ada? �The compiler shows some
>> errors. �After correcting these formally, i.e. without thinking,
>> it confirms Adam's observation, and hints to others:
>>
>> Compiling: printdirectory.adb (source file time stamp: 2009-09-24 06:42:50)
>>
>> � � 25. � EntryList � � � �: array (1..MaxEntries) of DirectoryEntryType;
>> � � � � � |
>> � � � � >>> warning: variable "EntryList" is not referenced
>>
>> � � 33. � � NewEntry.NamePart := To_Bounded_String(Buffer(1..Length));
>> � � � � � � |
>> � � � � >>> warning: "NewEntry" may be null
>>
>> Here, the "correction" was
>> 1 - �END IF; �-- semicolon, not colon
>> ...
>> 2, 3 - � �EntryPointerList(NumberOfEntries) := -- *new*
>> DirectoryEntry*Pointer*Type'(NewEntry); �-- MY QUESTION HERE
>>
>> (NewEntry is of a pointer type already.)
>
>That's the error.  NewEntry should not be a pointer type.  The intent
>appears to be that a record of type DirectoryEntryType is built, and
>then a copy of it allocated on the heap and the pointer stored in the
>array.  (I'm assuming that's the case; I don't have Cohen's book
>handy.)
>
>So the declaration of NewEntry is wrong.  Perhaps that has to do with
>a misunderstanding of the relationship between pointers and data; but
>I think it's more likely just a typographical error, made harder to
>spot by the lack of underscores.

Thanks Adam.  One of my problems here is that the example using
pointers is not declared in its entirety, but modified from a prev
example in the book.  I did not understand what had to be modified and
what remained.

And I haven't attempted to understand section 8.5.4 yet.