A code snippet: Controlled retry

[Hal Fulton]

I sometimes find myself retrying operations when in a networked
situation (e.g., maybe server isn't up, just try again).

I just wrote this little bit of code.

Tell me what you think... I'm sure it can be improved.

Cheers,
Hal


def try(quiet=true,times=5,secs=1,&block)
count = 0
catch :finished do
begin
block.call
rescue => err
puts "Error was: #{err}" if not quiet
count += 1
throw :finished if count > times
sleep secs
retry
end
end
end

[Gennady]

On Nov 23, 2003, at 22:11, Hal Fulton wrote:

> def try(quiet=true,times=5,secs=1,&block)
> count = 0
> catch :finished do
> begin
> block.call
> rescue => err
> puts "Error was: #{err}" if not quiet
> count += 1
> throw :finished if count > times
> sleep secs
> retry
> end
> end
> end

def try(quiet=true,times=5,secs=1,&block)
return unless block
times.times do
begin
return block.call
rescue => err
puts "Error was: #{err}" unless quiet
sleep secs
end
end
end


Sincerely,
Gennady Bystritsky

[Gennady]

On Nov 23, 2003, at 23:02, Gennady wrote:

>
> On Nov 23, 2003, at 22:11, Hal Fulton wrote:
>

>> def try(quiet=true,times=5,secs=1,&block)
>> count = 0
>> catch :finished do
>> begin
>> block.call
>> rescue => err
>> puts "Error was: #{err}" if not quiet
>> count += 1
>> throw :finished if count > times
>> sleep secs
>> retry
>> end
>> end
>> end

>
>
> def try(quiet=true,times=5,secs=1,&block)
> return unless block
> times.times do
> begin
> return block.call
> rescue => err
> puts "Error was: #{err}" unless quiet
> sleep secs
> end
> end
> end
>

Oops, times.times should become times.next.times to function like the
original. Also, when all attempts are exhausted, the last exception
must be re-raised or another more appropriate one raised (boolean
return would also do the trick).

[Robert Klemme]

"Gennady" <bystr@mac.com> schrieb im Newsbeitrag
news:4BB0276B-1E4F-11D8-A73D-0003939AEA24@mac.com...

> On Nov 23, 2003, at 23:02, Gennady wrote:
>

> >
> > On Nov 23, 2003, at 22:11, Hal Fulton wrote:
> >

> >> def try(quiet=true,times=5,secs=1,&block)
> >> count = 0
> >> catch :finished do
> >> begin
> >> block.call
> >> rescue => err
> >> puts "Error was: #{err}" if not quiet
> >> count += 1
> >> throw :finished if count > times
> >> sleep secs
> >> retry
> >> end
> >> end
> >> end

> >
> >
> > def try(quiet=true,times=5,secs=1,&block)
> > return unless block
> > times.times do
> > begin
> > return block.call
> > rescue => err
> > puts "Error was: #{err}" unless quiet
> > sleep secs
> > end
> > end
> > end
> >

>
> Oops, times.times should become times.next.times to function like the
> original. Also, when all attempts are exhausted, the last exception
> must be re-raised or another more appropriate one raised (boolean
> return would also do the trick).

Combining the two of them (i.e. times.next and re-raising) by simply
adding a line,
plus adding a check to allow for non-sleeping retries,
plus output parameter that can be an IO or an Array,
plus changed the first return to an exception in order to let the user
know he forgot something:

def try(times=0, secs=nil, log=nil, &block)
raise LocalJumpError, "no block given" unless block

times.times do
begin
return block.call
rescue => err
log << "Error was: #{err}\n" if log
sleep secs if secs
end
end

block.call
end

Cheers

robert