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50 lines
1.5 KiB
Markdown
50 lines
1.5 KiB
Markdown
# 5.3.13 select
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This module provides functions to wait for events on streams \(select streams which are ready for operations\).
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## Pyboard specifics
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Polling is an efficient way of waiting for read/write activity on multiple objects. Current objects that support polling are: pyb.UART, pyb.USB\_VCP.
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## Functions
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### select.poll\(\)
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Create an instance of the `Poll` class.
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### select.select\(rlist, wlist, xlist\[, timeout\]\)
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Wait for activity on a set of objects.
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This function is provided for compatibility and is not efficient. Usage of `Poll` is recommended instead.
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### class Poll
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## Methods
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### poll.register\(obj\[, eventmask\]\)
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Register `obj` for polling. `eventmask` is logical OR of:
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* `select.POLLIN` - data available for reading
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* `select.POLLOUT` - more data can be written
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* `select.POLLERR` - error occurred
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* `select.POLLHUP` - end of stream/connection termination detected
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`eventmask` defaults to `select.POLLIN | select.POLLOUT`.
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### poll.unregister\(obj\)
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Unregister `obj` from polling.
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### poll.modify\(obj, eventmask\)
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Modify the `eventmask` for `obj`.
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### poll.poll\(\[timeout\]\)
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Wait for at least one of the registered objects to become ready. Returns list of \(`obj`, `event`, ...\) tuples, `event` element specifies which events happened with a stream and is a combination of `select.POLL*` constants described above. There may be other elements in tuple, depending on a platform and version, so don’t assume that its size is 2. In case of timeout, an empty list is returned.
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Timeout is in milliseconds.
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