On Wed, Feb 22, 2017 at 5:59 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Ah, I see why *that* wants to know about it ... I think. I suppose you're arguing that variable expansion shouldn't be able to insert, say, an \else in a non-active branch? Maybe, but if it can insert an \else in an active branch, then why not non-active too? Seems a bit inconsistent.
The major reason was avoiding situations like what Daniel showed: where value of a variable that is meaningless/undefined in the current false-block context gets expanded anyway, and thus code inside a false block has effects outside of that block. Granted, his example was contrived. I'm open to removing that feature and seeing what breaks in the test cases.
Welcome to v15, highlights:
- all conditional data structure management moved to conditional.h and conditional.c
- conditional state lives in mainloop.c and is passed to HandleSlashCommands, exec_command and get_prompt as needed
- no more pset.active_branch, uses conditional_active(conditional_stack) instead
- PsqlScanState no longer has branching state
- Implements the %R '@' prompt on false branches.
- Variable expansion is never suppressed even in false blocks, regression test edited to reflect this.
- ConditionalStack could morph into PsqlFileState without too much work.
