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f-strings(Python 3.6) style literal string interpolation.

Project description

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Using f-strings(PEP 498) style literal string interpolation without Python 3.6.

Usages

  • Accessing the globals and locals.

    import os
    import fmt as f
    
    g_foo = 'global-foo'
    g_bar = 'global-bar'
    g_num = 23
    g_ls = [1, 2, 3]
    
    def scope():
        l_foo = 'local-foo'
        l_bar = 'local-bar'
        print( f('{l_foo}, {l_bar}') )    # 'local-foo, local-bar'
        print( f('{g_foo}, {g_bar!r}') )  # "global-foo, 'global-bar'"
    
    scope()
    print( f('{{ }}') )                   # '{ }'
    print( f('hex: {g_num:#x}') )         # '0x17'
    print( f('{os.EX_OK}') )              # '0'
    print( f('{g_ls[0]}, {g_ls[1]}, {g_ls[2]}') )  # '1, 2, 3'
    
  • NOTE: Closure will be a little tricky, must pass the outside scope variables as arguments to f, which added a reference to inside the closure in order this can work.

    import fmt as f
    
    def outer(x='xx'):
        y = 'yy'
        def inner():
            print( f('{x}, {y}', x, y) )  # "xx, yy"
        return inner
    
    outer()()
    
  • Expression evaluation.

    from datetime import datetime
    import fmt as f
    
    class S(object):
        def __str__(self):
            return 'hello'
        def __repr__(self):
            return 'hi'
        def __format__(self, fmt):
            return 'abcdefg'[int(fmt)]
    
    print( f('{1234567890:,}') )             # '1,234,567,890'
    print( f('{1 + 2}') )                    # '3'
    print( f('{str(1 + 2)!r}') )             # "'3'"
    print( f('{[i for i in range(5)]}') )    # '[0, 1, 2, 3, 4]'
    ls = range(5)
    print( f('{{i for i in ls}}') )          # 'set([0, 1, 2, 3, 4])' or '{0, 1, 2, 3, 4}'
    print( f('{{k:v for k,v in zip(range(3), range(3, 6))}}') )  # '{0: 3, 1: 4, 2: 5}'
    print( f('{datetime(1994, 11, 6):%Y-%m-%d}') )               # '1994-11-06'
    print( f('{list(map(lambda x: x+1, range(3)))}') )           # '[1, 2, 3]'
    print( f('{S()!s}, {S()!r}, {S():1}') )                      # 'hello, hi, b'
    
  • Also, you can register some namespaces for convenience.

    import fmt as f
    
    f.mregister({'x': 1, 'y': 2})  # register multiple
    f.register('z', 3)             # register only one
    
    def func(x, y):
        return x + y
    
    print( f('{func(x, y)}') )  # '3'
    print( f('{func(x, z)}') )  # '4'
    print( f('{func(y, z)}') )  # '5'
    
  • NOTE: locals() maybe cover the globals(), globals() maybe cover the namespaces that you registered.

Installation

Install by pip:

[sudo] pip install fmt -U

Project details


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