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From: ags@pucc-i (Dave Seaman)
Newsgroups: net.micro
Subject: Re: Turbo PASCAL quirk?
Message-ID: <922@pucc-i>
Date: Thu, 21-Feb-85 14:46:21 EST
Article-I.D.: pucc-i.922
Posted: Thu Feb 21 14:46:21 1985
Date-Received: Sun, 24-Feb-85 02:47:04 EST
References: <513@intelca.UUCP>
Distribution: net
Organization: Purdue University Computing Center
Lines: 44

>  What happens is that the line Sym_List := Nxt_Ident has no effect since
>  the With statement seems to lock you into the VALUE of the Sym_List 
>  pointer when you enter the With statement. Is this standard PASCAL?
>  I assumed, obviously incorrectly, that this code is equivalent to the
>  same code without the With and with all of the record fields prefixed 
>  with Sym_List^. 

The implementation is correct.  According to the American Pascal Standard,

	The record-variable shall be accessed before the statement
	of the with-statement is executed, and that access shall
	establish a reference to the variable during the entire
	execution of the statement of the with-statement.

The line Sym_List := Nxt_Ident does indeed have an effect (it changes
the value of Sym_List), but it does not affect the record-variable
access which is effective for the entire duration of the with-statement.

By the way, underscores in identifiers are not standard Pascal.

>  Type 
>    Ident_Ptr = ^Ident;
>    Ident = Record
>              Name       : String[127];
>              ID_Type    : Ident_Type;
>              References : Line_Ref;
>              Nxt_Ident  : Ident_Ptr;
>            End;
>  Var
>    Sym_List : Ident_Ptr;
>  
>  ...
>  
>    With Sym_List^ Do
>    Begin
>      While Name <> '' do
>      Begin
>        Writeln(Name);
>        Print_References(References);
>        Sym_List := Nxt_Ident;
>      End; (* While *)
>    End; (* With *) 
-- 
Dave Seaman			 ..!pur-ee!pucc-i:ags