what is the efficiency of an assign statement in progress-4gl

Question

why is an assign statement more efficient than not using assign?

co-workers say that:

assign
  a=3
  v=7
  w=8.

is more efficient than:

a=3.
v=7.
w=8.

why?

Answer 1

You could always test it yourself and see... but, yes, it is slightly more efficient. Or it was the last time I tested it. The reason is that the compiler combines the statements and the resulting r-code is a bit smaller.

But efficiency is almost always a poor reason to do it. Saving a micro-second here and there pales next to avoiding disk IO or picking a more efficient algorithm. Good reasons:

0. Back in the dark ages there was a limit of 63k of r-code per program. Combining statements with ASSIGN was a way to reduce the size of r-code and stay under that limit (ok, that might not be a "good" reason). One additional way this helps is that you could also often avoid a DO ... END pair and further reduce r-code size.

1. When creating or updating a record the fields that are part of an index will be written back to the database as they are assigned (not at the end of the transaction) -- grouping all assignments into a single statement helps to avoid inconsistent dirty reads. Grouping the indexed fields into a single ASSIGN avoids writing the index entries multiple times. (This is probably the best reason to use ASSIGN.)

2. Readability -- you can argue that grouping consecutive assignments more clearly shows your intent and is thus more readable. (I like this reason but not everyone agrees.)