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ch18: update from book draft

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This commit is contained in:
Luciano Ramalho 2020-02-19 00:15:20 -03:00
parent d63b4844f1
commit 0ca34e2676
3 changed files with 22 additions and 22 deletions
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16
18-context-mngr/mirror.py
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@ -4,7 +4,7 @@ A "mirroring" ``stdout`` context.
While active, the context manager reverses text output to While active, the context manager reverses text output to
``stdout``:: ``stdout``::
# BEGIN MIRROR_DEMO_1 # tag::MIRROR_DEMO_1[]
>>> from mirror import LookingGlass >>> from mirror import LookingGlass
>>> with LookingGlass() as what: # <1> >>> with LookingGlass() as what: # <1>
@ -18,12 +18,12 @@ While active, the context manager reverses text output to
>>> print('Back to normal.') # <5> >>> print('Back to normal.') # <5>
Back to normal. Back to normal.
# END MIRROR_DEMO_1 # end::MIRROR_DEMO_1[]
This exposes the context manager operation:: This exposes the context manager operation::
# BEGIN MIRROR_DEMO_2 # tag::MIRROR_DEMO_2[]
>>> from mirror import LookingGlass >>> from mirror import LookingGlass
>>> manager = LookingGlass() # <1> >>> manager = LookingGlass() # <1>
@ -40,11 +40,11 @@ This exposes the context manager operation::
>>> monster >>> monster
'JABBERWOCKY' 'JABBERWOCKY'
# END MIRROR_DEMO_2 # end::MIRROR_DEMO_2[]
The context manager can handle and "swallow" exceptions. The context manager can handle and "swallow" exceptions.
# BEGIN MIRROR_DEMO_3 # tag::MIRROR_DEMO_3[]
>>> from mirror import LookingGlass >>> from mirror import LookingGlass
>>> with LookingGlass(): >>> with LookingGlass():
@ -63,12 +63,12 @@ The context manager can handle and "swallow" exceptions.
... ...
NameError: name 'no_such_name' is not defined NameError: name 'no_such_name' is not defined
# END MIRROR_DEMO_3 # end::MIRROR_DEMO_3[]
""" """
# BEGIN MIRROR_EX # tag::MIRROR_EX[]
class LookingGlass: class LookingGlass:
def __enter__(self): # <1> def __enter__(self): # <1>
@ -89,4 +89,4 @@ class LookingGlass:
# <11> # <11>
# END MIRROR_EX # end::MIRROR_EX[]

12
18-context-mngr/mirror_gen.py
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@ -4,7 +4,7 @@ A "mirroring" ``stdout`` context manager.
While active, the context manager reverses text output to While active, the context manager reverses text output to
``stdout``:: ``stdout``::
# BEGIN MIRROR_GEN_DEMO_1 # tag::MIRROR_GEN_DEMO_1[]
>>> from mirror_gen import looking_glass >>> from mirror_gen import looking_glass
>>> with looking_glass() as what: # <1> >>> with looking_glass() as what: # <1>
@ -16,12 +16,12 @@ While active, the context manager reverses text output to
>>> what >>> what
'JABBERWOCKY' 'JABBERWOCKY'
# END MIRROR_GEN_DEMO_1 # end::MIRROR_GEN_DEMO_1[]
This exposes the context manager operation:: This exposes the context manager operation::
# BEGIN MIRROR_GEN_DEMO_2 # tag::MIRROR_GEN_DEMO_2[]
>>> from mirror_gen import looking_glass >>> from mirror_gen import looking_glass
>>> manager = looking_glass() # <1> >>> manager = looking_glass() # <1>
@ -38,12 +38,12 @@ This exposes the context manager operation::
>>> monster >>> monster
'JABBERWOCKY' 'JABBERWOCKY'
# END MIRROR_GEN_DEMO_2 # end::MIRROR_GEN_DEMO_2[]
""" """
# BEGIN MIRROR_GEN_EX # tag::MIRROR_GEN_EX[]
import contextlib import contextlib
@ -61,4 +61,4 @@ def looking_glass():
sys.stdout.write = original_write # <6> sys.stdout.write = original_write # <6>
# END MIRROR_GEN_EX # end::MIRROR_GEN_EX[]

16
18-context-mngr/mirror_gen_exc.py
View File

@ -4,7 +4,7 @@ A "mirroring" ``stdout`` context manager.
While active, the context manager reverses text output to While active, the context manager reverses text output to
``stdout``:: ``stdout``::
# BEGIN MIRROR_GEN_DEMO_1 # tag::MIRROR_GEN_DEMO_1[]
>>> from mirror_gen import looking_glass >>> from mirror_gen import looking_glass
>>> with looking_glass() as what: # <1> >>> with looking_glass() as what: # <1>
@ -16,12 +16,12 @@ While active, the context manager reverses text output to
>>> what >>> what
'JABBERWOCKY' 'JABBERWOCKY'
# END MIRROR_GEN_DEMO_1 # end::MIRROR_GEN_DEMO_1[]
This exposes the context manager operation:: This exposes the context manager operation::
# BEGIN MIRROR_GEN_DEMO_2 # tag::MIRROR_GEN_DEMO_2[]
>>> from mirror_gen import looking_glass >>> from mirror_gen import looking_glass
>>> manager = looking_glass() # <1> >>> manager = looking_glass() # <1>
@ -38,7 +38,7 @@ This exposes the context manager operation::
>>> monster >>> monster
'JABBERWOCKY' 'JABBERWOCKY'
# END MIRROR_GEN_DEMO_2 # end::MIRROR_GEN_DEMO_2[]
The context manager can handle and "swallow" exceptions. The context manager can handle and "swallow" exceptions.
The following test does not pass under doctest (a The following test does not pass under doctest (a
@ -46,7 +46,7 @@ ZeroDivisionError is reported by doctest) but passes
if executed by hand in the Python 3 console (the exception if executed by hand in the Python 3 console (the exception
is handled by the context manager): is handled by the context manager):
# BEGIN MIRROR_GEN_DEMO_3 # tag::MIRROR_GEN_DEMO_3[]
>>> from mirror_gen import looking_glass >>> from mirror_gen import looking_glass
>>> with looking_glass(): >>> with looking_glass():
@ -57,7 +57,7 @@ is handled by the context manager):
ytpmuD ytpmuH ytpmuD ytpmuH
Please DO NOT divide by zero! Please DO NOT divide by zero!
# END MIRROR_GEN_DEMO_3 # end::MIRROR_GEN_DEMO_3[]
>>> with looking_glass(): >>> with looking_glass():
... print('Humpty Dumpty') ... print('Humpty Dumpty')
@ -73,7 +73,7 @@ is handled by the context manager):
""" """
# BEGIN MIRROR_GEN_EXC # tag::MIRROR_GEN_EXC[]
import contextlib import contextlib
@ -98,4 +98,4 @@ def looking_glass():
print(msg) # <4> print(msg) # <4>
# END MIRROR_GEN_EXC # end::MIRROR_GEN_EXC[]