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| 311 | |
311 | |
| 312 | =item @states = Coro::State::list |
312 | =item @states = Coro::State::list |
| 313 | |
313 | |
| 314 | Returns a list of all states currently allocated. |
314 | Returns a list of all states currently allocated. |
| 315 | |
315 | |
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316 | =item $clone = $state->clone |
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317 | |
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318 | This exciting method takes a Coro::State object and clones, i.e., creates |
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319 | a copy. This makes it possible to restore a state more than once. |
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320 | |
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321 | Since its only known purpose is intellectual self-gratification, and |
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322 | because it is a difficult piece of code, it is not enabled by default, and |
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323 | not supported. |
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324 | |
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325 | Among the games you can play with this is implement a scheme-like call/cc: |
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326 | |
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327 | sub callcc(&@) { |
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328 | my ($f, @arg) = @_; |
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329 | |
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330 | my $c = new Coro::State; |
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331 | |
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332 | my $F; $F = new Coro::State sub { |
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333 | $f->( |
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334 | sub { |
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335 | @arg = @_; |
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336 | $F->transfer ($c->clone); |
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337 | }, |
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338 | @arg |
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339 | ); |
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340 | }; |
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341 | |
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342 | $c->transfer ($F); |
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343 | @arg |
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344 | } |
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345 | |
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346 | Here are a few little-known facts: First, coroutines *are* full/true/real |
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347 | continuations. Secondly Coro::State objects (without clone) *are* first |
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348 | class continuations. Thirdly, nobody has ever found a use for the full |
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349 | power of call/cc that isn't better (faster, easier, more efficient) |
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350 | implemented differently, and nobody has yet found a useful control |
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351 | construct that can't be implemented without it already, just much faster |
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352 | and with fewer resources. |
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353 | |
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354 | Besides, call/cc is much less useful in a Perl-like dynamic language (with |
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355 | references, and its scoping rules) then in, say, scheme. |
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356 | |
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357 | Now, limitations of clone: |
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358 | |
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359 | It probably only works on perl 5.10; it cannot clone a coroutine inside |
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360 | the substition opertaor (but windows perl can't fork from there either), |
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361 | and C<abort ()> is the preferred mechanism to signal errors. It probbaly |
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362 | also leaks, and sometimes triggers a few assertions inside Coro. Most of |
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363 | these limitations *are* fixable with some effort, but that's pointless |
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364 | just to make a point that it could be done. |
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365 | |
| 316 | =cut |
366 | =cut |
| 317 | |
367 | |
| 318 | # used by Coro::Debug only atm. |
368 | # used by Coro::Debug only atm. |
| 319 | sub debug_desc { |
369 | sub debug_desc { |
| 320 | $_[0]{desc} |
370 | $_[0]{desc} |
