Hi All,

what is the use of LET in 'LET NOPRINT '.

thanks
RP

This message has been edited. Last edited by: Kerry,

Without a right hand component it means nothing.

What's to the right of the =

Is it

LET NOPRINT = ;
LET NOPRINT = 'Happy Christmas'

Where is it coded

in a focexec or edasprof.prf or another profile file?

LET is a way of creating substitutes.
For instance, if I specify LET RP=TABLE, I could code RP FILE CAR PRINT *
It means that RP gets substituted by TABLE at runtime.

That is useful, we use &qout;param for these kind of constructions...

Why isn't LET documented?
(it's not to be found in the 'help')

Legacy?

Yes, it is a legacy thing. Although I know that it exists, I never use it.
It used to work fine with Focus, but I tried it once in WebFocus and it failed for some odd reason. So I decided to let LET be and never used it again.

Like the Beatles would say..

Let LET be.

Hi RP,

Suggestion from our technicals:

As mentioned, the use of LET will create a substitution. In the case of:

LET NOPRINT=;

a substitution is generated so that when FOCUS sees NOPRINT, it will be replaced by blank. This is an interesting way to prevent people from using NOPRINT in their code. Try this:

LET NOPRINT=;
TABLE FILE CAR
PRINT COUNTRY NOPRINT
END

Notice that COUNTRY will still show up in the output.

Cheers,

Kerry

Old, no documentation number and notice the word legacy in the URL

WebFOCUS Defining a Word Substitution

This message has been edited. Last edited by: <JG>,

While LET is cool, I never had much use for it except for OS commands. For example, say one wants to delete a file. In Windows one might do:

-DOS DEL path/filename

while in UNIX or Linux it would be

-UNIX rm path/filename

One could put the following in the edasprof

LET OSDEL=-UNIX rm

and use the following in the code:

OSDEL path/filename

So if the code might run on a Windows and a Linux reporting server, doing something like this keeps one from having to change code when moving between environments. All one has to do is change OSDEL in the edasprof of the Reporting Server.

I'd say it's a fairly powerful debugging tool. Say you have a graph that doesn't display what it should be displaying. You put

LET GRAPH=TABLE;

in your fex and you can see what values it's using.

I haven't tried, but you could for example conditionally create a GRAPH or a TABLE.
Like so:

-GOTO TYPE_&OUTPUTFORMAT
-TYPE_TABLE
LET OUTPUT = TABLE;
LET FMT = HTML;
-GOTO TYPE_END

-TYPE_GRAPH
LET OUTPUT = GRAPH;
LET FMT = PNG;
-TYPE_END

OUTPUT FILE CAR
PRINT WIDTH
BY LENGTH
ON TABLE PCHOLD FORMAT FMT
END

Of course you need to be very careful not to accidentally overwrite a core Focus command, that would give some interesting results for sure!

You can do the same using ampersand-variables, but you'll frequently find you need to eval them.

As a software engineer I find the use of LET to be a great trick. As a manager of many software engineers I would bar the use of LET in any production software.

Think of the poor guy trying to maintain a 500 line fex who sees GRAPH ... but getting TABLE?!?! All because much further up in the fex there is a -INCLUDE and the included file did some trickery that CHANGES the language.

If you use &VARs the subsequent readers KNOW there is a substitution.

(getting off my sandbox).

Certainly true, it's as powerful a tool as it is dangerous.

I also just found out that you apparently can't use it for number formatting :/

-* File let.fex
TABLE FILE CAR
PRINT WEIGHT/P12.2
BY CAR
END

LET WGT = P12.2

TABLE FILE CAR
PRINT WEIGHT/WGT
BY CAR
END

-*0 ERROR AT OR NEAR LINE     10  IN PROCEDURE let     FOCEXEC *
-*(FOC035) ERROR IN THE FORMAT OF THE COMPUTED FIELD DEFINITION: WEIGHT/WGT
-*BYPASSING TO END OF COMMAND
-*(FOC009) INCOMPLETE REQUEST STATEMENT