schrodinger.infra.util module

General infrastructure level utilities.

Copyright Schrodinger, LLC. All rights reserved.

class schrodinger.infra.util.cached_property(func)

Bases: object

Decorator that converts a method with a single self argument into a property cached on the instance.

Use del to delete the currently cached value and force a recalculation on the next access. See the tests for examples.

This class is based on code that is Copyright (c) Django Software Foundation

class schrodinger.infra.util.CreateWhenNeeded(function, name=None, doc=None)

Bases: object

This class can be used like property() (i.e., it is a descriptor; see section 3.3.2.2 in the python reference). It will hold off on creating the object until it is needed, but once it has been created it will return the object directly.

It’s best used for attributes that are expensive to calculate (as measured by profiling, of course) and not always used.

class schrodinger.infra.util.OneIndexedList

Bases: list

A list that starts at one instead of zero

index(value[, start[, stop]]) → integer -- return first index of value.

Raises ValueError if the value is not present.

insert(i, x)

L.insert(index, object) – insert object before index

pop([index]) → item -- remove and return item at index (default last).

Raises IndexError if list is empty or index is out of range.

schrodinger.infra.util.flag_context_manager(attr_name, set_to=True)

Create a context manager that sets the specified class attribute to the given value and then restores the original value of the attribute when leaving the context.

Example:

class Foo(object):

_includingStructure = util.flag_context_manager(“_including_structure”)

def __init__(self):
self._including_structure = False
def includeStructure(proj_row):
with self._includingStructure():
proj_row.in_workspace = project.IN_WORKSPACE
See:

skip_if
Parameters:
  • attr_name (str) – The attribute to set to set_to
  • set_to (object) – The value to set attr_name to
schrodinger.infra.util.skip_if(attr_name, if_set_to=True)

Create a decorator that converts the decorated method to a no-op if class attribute attr_name equals is_set_to.

Example:

skip_if_including_structure = util.skip_if("_including_structure")

class Foo(object):
    _includingStructure = util.flag_context_manager("_including_structure")
    def __init__(self):
        self._including_structure = False

    def includeStructure(proj_row):
        with self._includingStructure():
            proj_row.in_workspace = project.IN_WORKSPACE

    @skip_if_including_structure
    def skipped_method(self):
        print ("This method would have been skipped if we were the process "
               "of including a structure")
See:

flag_context_manager
Parameters:
  • attr_name (str) – The attribute name to check
  • if_set_to (object) – The decorated method will be skipped if attr_name equals this value.
schrodinger.infra.util.enum_speedup(enum_cls)

Add all enum members to a new class to speed up access.

Attribute access in enum classes is incredibly slow (see https://bugs.python.org/issue23486). Previously, it accounted for roughly 7.5% of the runtime of scrolling in the HPT. Use of this function reduced that time to nearly zero.

Parameters:enum_cls (enum.Enum) – The enum class to wrap.
Returns:A new class that allows for faster access of the enum members.
Return type:object
Note:Enums have been significantly sped up in Python 3.5, but that speed up hasn’t yet been backported to the Python 2 enum backport. See the Python bug linked above.
Note:Declaring a Qt signal with an argument type of a sped-up enum class

will lead to a TypeError when you try to emit an enum member (since Qt doesn’t pay attention to __instancecheck__). Use object in the signal declaration instead. In other words, use

mySignal = QtCore.pyqtSignal(object)

instead of

mySignal = QtCore.pyqtSignal(MySpedUpEnum)