Lorenzo Fiorini wrote:
Thanks to great Mindaugas' -w3 addition I've done a major cleanup of my apps.
I wonder if the compiler can detect if a local var is used before assigned.
function main
local nVar
nVar := nVar + 1
return nVar
Hi,
it can detect, but...
In Harbour variables are (kind of) assigned to NIL on its' defnintion,
and this fact is often used by programmers. We often do, something like:
LOCAL xI
FOR nI := 1 TO ..
IF xI == NIL // xI is unassigned on first cycle of the loop
...
ENDIF
...
NEXT
or:
PROC MY_MD5FILE(...)
LOCAL cMD5
DO WHILE ( cBuf := READBUF(...) ) != NIL
cMD5 := HB_MD5( cBuf, cMD5 ) // cMD5 is unassigned on first cycle
ENDDO
RETURN cMD5
So,
LOCAL nVar
nVar := nVar + 1
is kind of
LOCAL nVar := NIL
nVar := nVar + 1
problem.
But it is not problem of unassigned variable, it is problem of operation
plus (NIL + NUMERIC). Some error detection could be done now, but
expression tree and general infrastructure of typed variables/values in
compiler can help to find much more errors, ex.:
nVar := NIL
nVar += LEN(aI)
So, I do not want to do a partial implementation of this based on pcode
analysis.
Best regards,
Mindaugas
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