# [Python-ideas] datetime.timedelta literals

Pål Grønås Drange paal.drange at gmail.com
Mon Jun 4 06:59:22 EDT 2018

```One thing that could solve both this proposal and the aforementioned
SI-proposition by Ken Kundert, could be supporting user-defined
literals.  Suppose that __litXXX___ would make XXX a literal one could
use as a suffix for numbers and strings (and lists, dicts, sets?).

A user-defined literal could be defined as __lit<insert literal>__,
though I don't know how to import it.

Anything without leading underscore could be preserved for the standard
library:

# In the standard library:

def __litj__(x):
return complex(0, x)

# The above example would make 2+3j work as expected

# In the datetime module
def __lit_h__(x):
return timedelta(hours=x)

def __lit_min__(x):
return timedelta(minutes=x)

# In the Pint (units) module for dimensional analysis
def __lit_km__(x):
return x * pint.UnitRegistry().km

# It wouldn't be limited to numbers

def __lit_up__(x):
return x.upper()

s = 'literal'_up  # s = LITERAL

# The _(x) from Django could be written

def __lit_T__(x):
return translate(x)

s = 'literal'_T  # s = translate('literal')

# Heck, it could even be written as (abusing(?) notation)
def __lit___(x):
return translate(x)

s = 'literal'_  # s = translate('literal')

If we want to abuse the literals more, one could make

def __lit_s__(lst):
"""Makes a list into a sorted list"""
return sortedlist(lst)

heap = []_s  # heap is of type sortedlist

- Pål
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