For and If with one line: to brace or not to brace

For one-line if I prefer postconditionals:

set:a b=a

As for For - the option with braces. It's more readable. And one line inside For loop quickly and often becomes several lines, so braces become mandatory anyway.

Yep, brace always.

Because you will never know if you need to update your condition or chain another. The brace shows what is the scope of the condition, also for loops, for, for each, etc.

It is a good practices and it is more readable.

As Eduard Lebedyuk   has commented, a single IF for use to set a variable, the postconditionals is a good idea, coz you know the condition before to set.

Postcondition is preferred
especially  quit:error     or   continue:ignore

for i=1:1:5 write i," "     is as fine as    for i=1:1:5 {  write i," " } write "end"

but this is really bad:

Besides all that is mentioned, the If without braces has a side-effect that the If with braces does not have : it affects the system variable $Test.

USER>set $test=0
 
USER>w $test
0
USER>if 1=1 { write "one" }
one
USER>w $test
0
USER>if 1=1 write "one"
one
USER>w $test
1
USER>

Not important, only if you use the ELSE (legacy) command...

We want our code to be as accessible and readable as possible to as many people as possible. We always prefer whitespace formatting and curly brackets to arcane one line syntax. Someone who's not an Object Script expert will know what this does -

if a { 
   set b=a 
}

But there's no guarantee that a novice will necessarily know what these do -

if a set b=a

set:a b=a

Good code is readable and clever one liners will get in the way of that goal.

The legacy versions of If and For commands don't use curly braces. But there are no legacy versions of While and Do/While, which require curly braces. So rather than trying to remember which commands use or don't use curly braces, just use curly braces all the time for these, as well as Try/Catch.

Regarding post-conditionals, it's a good habit to put parentheses around the condition, which allows you to put spaces in the condition.

This is valid syntax: set:a=4 y=10

This is valid syntax and more readable: set:(a = 4) y = 10

This is invalid syntax: set:a = 4 y = 10

I just went through the whole conversation on this and find it knowledgeable for me as i am beginner for cache. Now i am able to understand how to use them in with the standards and where i need to careful thanks for all. 

If I am modifying a routine I didn't originally write then I tend to stick to the coding style the original author adopted - even it is using legacy syntax. It is good practice not to mix old and new constructs within the same code block ie. don't mix curly braces with line-oriented syntax.  If you are completely re-writing something or writing new code then I prefer curly braces.

I would have liked to re-factor some of my code better but I found the 'use for' construct breaks when you try that. In this pseudocode, I was using the 'write' statement to write to a file on the file system. There is a condition that is checked to determine whether it gets written to file1 or file2.

 The article is considered as InterSystems Data Platform Best Practice.