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%global _empty_manifest_terminate_build 0
Name: python-lazy-property
Version: 0.0.1
Release: 1
Summary: Makes properties lazy (ie evaluated only when called)
License: MIT
URL: https://github.com/jackmaney/lazy-property.git
Source0: https://mirrors.nju.edu.cn/pypi/web/packages/1c/97/55bf318faf296b254a20e80657b439b019fd809d4aabc1e55d7788f75401/lazy-property-0.0.1.tar.gz
BuildArch: noarch
%description
`Properties <https://docs.python.org/3.4/library/functions.html#property>`_ are a very useful feature of Python, effectively allowing an attribute to masquerade as a method (with no arguments other than ``self``). However, sometimes we want to store the results of an expensive computation in an attribute. The straightforward way to do it would be something like the following:
import time
def do_some_big_calculation():
"""Simulating some ginormous calculation going on somewhere..."""
print("{}: Calculations started...".format(time.time))
time.sleep(5)
print("{}: Calculations complete!".format(time.time))
return 42
class SomeClass(object):
def __init__(self):
self.calculation_value = do_some_big_calculation()
And that certainly works. However, this means that whenever you instantiate an object from ``SomeClass``, you'll perform this calculation each time. That could be problematic...
So, what we really want is for this calculation to only be done when it's needed. In other words, what we want is for this attribute to be **lazy**.
To do that, you can create a property, and a "private" attribute, named ``_calculation_value``, used to cache the result, like so:
class SomeOtherClass(object):
@property
def calculation_value(self):
if not hasattr(self, "_calculation_value"):
self._calculation_value = do_some_big_calculation()
return self._calculation_value
This package essentially reduces this down to a decorator:
import lazy_property
class YetAnotherClass(object):
@lazy_property.LazyProperty
def calculation_value(self):
return do_some_big_calculation()
And when called, the "calculation" is only done once:
In [5]:yac = YetAnotherClass()
In [6]: yac.calculation_value
1440798443.228256: Calculations started...
1440798448.229179: Calculations complete!
Out[6]: 42
In [7]: yac.calculation_value
Out[7]: 42
Note, however, that this property is not writable:
%package -n python3-lazy-property
Summary: Makes properties lazy (ie evaluated only when called)
Provides: python-lazy-property
BuildRequires: python3-devel
BuildRequires: python3-setuptools
BuildRequires: python3-pip
%description -n python3-lazy-property
`Properties <https://docs.python.org/3.4/library/functions.html#property>`_ are a very useful feature of Python, effectively allowing an attribute to masquerade as a method (with no arguments other than ``self``). However, sometimes we want to store the results of an expensive computation in an attribute. The straightforward way to do it would be something like the following:
import time
def do_some_big_calculation():
"""Simulating some ginormous calculation going on somewhere..."""
print("{}: Calculations started...".format(time.time))
time.sleep(5)
print("{}: Calculations complete!".format(time.time))
return 42
class SomeClass(object):
def __init__(self):
self.calculation_value = do_some_big_calculation()
And that certainly works. However, this means that whenever you instantiate an object from ``SomeClass``, you'll perform this calculation each time. That could be problematic...
So, what we really want is for this calculation to only be done when it's needed. In other words, what we want is for this attribute to be **lazy**.
To do that, you can create a property, and a "private" attribute, named ``_calculation_value``, used to cache the result, like so:
class SomeOtherClass(object):
@property
def calculation_value(self):
if not hasattr(self, "_calculation_value"):
self._calculation_value = do_some_big_calculation()
return self._calculation_value
This package essentially reduces this down to a decorator:
import lazy_property
class YetAnotherClass(object):
@lazy_property.LazyProperty
def calculation_value(self):
return do_some_big_calculation()
And when called, the "calculation" is only done once:
In [5]:yac = YetAnotherClass()
In [6]: yac.calculation_value
1440798443.228256: Calculations started...
1440798448.229179: Calculations complete!
Out[6]: 42
In [7]: yac.calculation_value
Out[7]: 42
Note, however, that this property is not writable:
%package help
Summary: Development documents and examples for lazy-property
Provides: python3-lazy-property-doc
%description help
`Properties <https://docs.python.org/3.4/library/functions.html#property>`_ are a very useful feature of Python, effectively allowing an attribute to masquerade as a method (with no arguments other than ``self``). However, sometimes we want to store the results of an expensive computation in an attribute. The straightforward way to do it would be something like the following:
import time
def do_some_big_calculation():
"""Simulating some ginormous calculation going on somewhere..."""
print("{}: Calculations started...".format(time.time))
time.sleep(5)
print("{}: Calculations complete!".format(time.time))
return 42
class SomeClass(object):
def __init__(self):
self.calculation_value = do_some_big_calculation()
And that certainly works. However, this means that whenever you instantiate an object from ``SomeClass``, you'll perform this calculation each time. That could be problematic...
So, what we really want is for this calculation to only be done when it's needed. In other words, what we want is for this attribute to be **lazy**.
To do that, you can create a property, and a "private" attribute, named ``_calculation_value``, used to cache the result, like so:
class SomeOtherClass(object):
@property
def calculation_value(self):
if not hasattr(self, "_calculation_value"):
self._calculation_value = do_some_big_calculation()
return self._calculation_value
This package essentially reduces this down to a decorator:
import lazy_property
class YetAnotherClass(object):
@lazy_property.LazyProperty
def calculation_value(self):
return do_some_big_calculation()
And when called, the "calculation" is only done once:
In [5]:yac = YetAnotherClass()
In [6]: yac.calculation_value
1440798443.228256: Calculations started...
1440798448.229179: Calculations complete!
Out[6]: 42
In [7]: yac.calculation_value
Out[7]: 42
Note, however, that this property is not writable:
%prep
%autosetup -n lazy-property-0.0.1
%build
%py3_build
%install
%py3_install
install -d -m755 %{buildroot}/%{_pkgdocdir}
if [ -d doc ]; then cp -arf doc %{buildroot}/%{_pkgdocdir}; fi
if [ -d docs ]; then cp -arf docs %{buildroot}/%{_pkgdocdir}; fi
if [ -d example ]; then cp -arf example %{buildroot}/%{_pkgdocdir}; fi
if [ -d examples ]; then cp -arf examples %{buildroot}/%{_pkgdocdir}; fi
pushd %{buildroot}
if [ -d usr/lib ]; then
find usr/lib -type f -printf "/%h/%f\n" >> filelist.lst
fi
if [ -d usr/lib64 ]; then
find usr/lib64 -type f -printf "/%h/%f\n" >> filelist.lst
fi
if [ -d usr/bin ]; then
find usr/bin -type f -printf "/%h/%f\n" >> filelist.lst
fi
if [ -d usr/sbin ]; then
find usr/sbin -type f -printf "/%h/%f\n" >> filelist.lst
fi
touch doclist.lst
if [ -d usr/share/man ]; then
find usr/share/man -type f -printf "/%h/%f.gz\n" >> doclist.lst
fi
popd
mv %{buildroot}/filelist.lst .
mv %{buildroot}/doclist.lst .
%files -n python3-lazy-property -f filelist.lst
%dir %{python3_sitelib}/*
%files help -f doclist.lst
%{_docdir}/*
%changelog
* Tue Apr 11 2023 Python_Bot <Python_Bot@openeuler.org> - 0.0.1-1
- Package Spec generated
|
