Re: HereDoc

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

Yeah, here-docs are kinda nice.  I use them from time-to-time in shell 
scripts...  I also used to use them a lot in perl (though, I rarely code 
in perl anymore.)

In RPG, I tend to solve the same problem by using CTDATA arrays.  For 
example:

     D MyData          s             80a   dim(20) ctdata
      /free
         ... put your code here ...
      /end-free
**
Update MCPSRV Set SESCLS='O',
   semdat = Date_As_Cymd(Current_Date),
   semtim = time_As_Hms(Current_Time), seuser = user,
   sempgm = 'SQL'
   Where SEICD9='V2020Z'

It's not in-line with the code like it would be with a here-doc, but 
that's proven to be a minor issue, not a major one.

Another approach is to use CGIDEV2's templating feature... maybe a bit 
overkill, but it gives you the ability to put your 'here-doc' in a stmf 
or pf-mbr, and you can have variables that get replaced with data, etc.

Another thing you may not have considered... you don't actually need to 
close the quotes, and open them again on every line (as you did in your 
example.)  You could've coded it a little simpler, like this:

         updateStmt =
          'Update MCPSRV Set SESCLS=''O'', +
             semdat = Date_As_Cymd(Current_Date), +
             semtim = time_As_Hms(Current_Time), seuser = user, +
             sempgm = ''SQL'' +
           Where SEICD9=''V2020Z''';

Not quite as nice as the CTDATA or here-doc approach, but it's a little 
nicer than what you had.

Don't get me wrong... I don't think a here-doc is a bad idea... it's a 
pretty good one (if implemented well), I just wanted to point out that 
there are other alternatives that might help you in the short term.


On 1/20/2011 8:46 AM, Mark Murphy/STAR BASE Consulting Inc. wrote:
> Some time ago I learned PHP, and was introduced to a concept called
> HereDoc.  Essentially a way to insert a string inline.  Didn't really see
> the use of it, and never really thought about it much until now.  I have a
> piece of code where it would be highly useful for improving the
> readability of my program.  Unfortunately  The use is in an RPG program,
> and the feature does not exist there.
>
> Anyway here is what I was thinking.  I am using dynamic SQL in a
> particular program (so that I can use set schema to direct unqualified
> references to the environment of my choice).  Some of the SQL commands are
> quite complex, and I have to double quotes in my string literals.  the
> whole thing degenerates into a bunch of extra quotes and continuation
> marks that would not be necessary with a HereDoc.
>
> Consider the following (very simple, but serves to make the point):
>
>         updateStmt =
>           'Update MCPSRV Set SESCLS=''O'',                        ' +
>           '  semdat = Date_As_Cymd(Current_Date),                 ' +
>           '  semtim = time_As_Hms(Current_Time), seuser = user,   ' +
>           '  sempgm = ''SQL''                                     ' +
>           'Where SEICD9=''V2020Z''';
>
> With a HereDoc I could write something like:
>
>         updateStmt =<<<DOC
>           Update MCPSRV Set SESCLS='O',
>             semdat = Date_As_Cymd(Current_Date),
>             semtim = time_As_Hms(Current_Time), seuser = user,
>             sempgm = 'SQL'
>           Where SEICD9='V2020Z'
>        <<<DOC
>
> Even with a simple example the lack of superfluous quotes and continuation
> marks makes the second far more readable than the first.
>
> Any thoughts?
>
> Mark Murphy
> STAR BASE Consulting, Inc.
> mmurphy@xxxxxxxxxxxxxxx