On Thu, 7 Sep 2017 17:03:06 -0700 (PDT)
Dorival Pedroso <pedr...@cpmech.com> wrote:
> Wouldn't be great to have a "syntactical sugar" to make things (at least a
> little bit) simpler in our beloved Go language?
No. Proposed (*also by past me*) "watch" construct is bad for anyone
reading code, bad for code consistency and is unable to provide any real
value in spite of high expectations. I coined it as a freshmen to Go then
I gave it up after few tries to "implement" it with code generator just after
"spooky action at distance is bad" turned out to be so true.
> Simpler would certainly encourage people to handle errors properly
"Watch" is NOT simpler. It bears "at distance" burden. It does not give
debugging person a way to know which call under watch went wrong.
The explicitness of if err!=nil { ... } is.
> Of course, we don't need the "watch" command for these. In fact, we need
> nothing special in Go to properly handle these errors.
Yes. And I have learned it weeks after my "I wanna watch" fool.
(The reason for "watch" was porting an ugly code to check validity of many
fields in complicated financial messages).
Had I have "watch" at hand I would end blindly (albeit automated) rewriting
try/catch spaghetti code for each MT. Fortunately I had no "watch" so I got
to the table, then to the map (for maintenance reasons. See here map:
https://play.golang.org/p/3PDgjCgPMK . Every try/catch block rewritten in
Go became simple call of validate(&MT, "ABA","SC","RSN") shape).
For SQL call chains you may use "For/Switch" pattern:
https://play.golang.org/p/0gWarQ8TL7 .
For/Switch is clear and can cope with e.g. retries for a 5 lines more:
https://play.golang.org/p/CyhIJabzFn
watch:
for i = 1; retry < 3; i++ {
if err != nil {
i--
retry++
continue
}
switch i {
case 1:
err = getData(i)
case 2:
err = getData(i)
case 3:
err = getData(i)
default:
break watch
}
}
if err != nil {
// handle common error
}
All above patterns have single err handling place yet give back information
where err was set -- something "watch" knows nothing about.
P.S. someone else proposed wrapper with error handling in defer.
IMO it is as bad as watch - spooky, at distance, clunky.
--
Wojciech S. Czarnecki
<< ^oo^ >> OHIR-RIPE
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