P - Glossary (Python)

Buy Me a Coffee☕

parameter (param)

• is a variable without or with a default value within a function header to receive zero or more arguments.
• is a general term to cover required, optional, positional-or-keyword, positional-only, keyword-only, var-positional and var-keyword parameter.
• E.g. def func(x, y = 3.14) -> None: ....
• I specifically use the term parameter for a function to receive values so I don't generally use it to also cover type parameter.

  • required parameter

  • is one which must receive an argument.
  • E.g. def func(x) -> None: ....

  • optional parameter

  • is one which may receive an argument.
  • E.g. def func(x = 100) -> None: ....

  • positional-or-keyword parameter (PK)

  • is one to receive a positional or keyword argument.
  • E.g. def func(x) -> None: ....

  • positional-only parameter (PO)

  • is one to receive a positional argument.
  • E.g. def func(x, /) -> None: ....

  • keyword-only parameter (KO)

  • is one to receive a keyword argument.
  • E.g. def func(*, x) -> None: ....

  • var-positional parameter (VP)

  • is one with a preceding unpack operator, e.g. *args to flexibly receive zero or more positional arguments as a tuple so the type is tuple.
  • is an optional parameter with the immutable default value () so the default value () cannot be changed with =.
  • E.g. def func(*args) -> None: ....
  • By convention, *args is used but other names can also be used like *teachers, *students, etc.
  • All the parameters after *args become keyonlyparams.
  • Only one *args can be used within a function header.

  • var-keyword parameter (VK)

  • is one to flexibly receive zero or more keyword arguments as a dictionary.
  • is an optional parameter with the immutable default value {} so the default value {} cannot be changed with =.
    • E.g. def func(**kwargs) -> None: ....
  • By convention, **kwargs is used but other names can also be used like **teachers, **students, etc.
  • Only one **kwargs can be used within a function header.

argument

• is a value passed to a parameter.

parameter type specification (paramtypespec)

• is code to specify the types and order of parameters.
• can also be called parameter specification(ParamSpec) but I use parameter type specification(paramtypespec) because it's more specific and there is no special reason to camelcase the abbreviation.

parameter type specification operator (paramtypespec operator)

• is ** to receive a parameter type specification:

# E.g.
class Cls[**P]: ...
v: Cls[[int, str]]

• only exists to receive a parameter type specification but not to unpack it.
• isn't an unpack operator.
• can also be called parameter specification operator(ParamSpec operator) but I use parameter type specification operator(paramtypespec operator) because it's more specific and there is no special reason to camelcase the abbreviation.

Python core (PyCo)

• is the Python's engine which consists of bytecode compiler(BC) and virtual box(VB) to repeat the cycle BC ➝ VM.
• can also be called Python interpreter(PyIn) but I use Python core because the interpreter of Python interpreter isn't very distinct from the compiler of bytecode compiler, which is confusing.

  • bytecode compiler (BC)

  • is a component of PyCo to check the syntax of Python code, then to compile the Python code into bytecode at compile time.

  • virtual machine (VM)

  • is a component of PyCo to run the bytecode compiled by bytecode compiler.
  • contains garbage collector.
  • infers dynamic types.

  • garbage collector

  • is a component of virtual machine to free the memory of no longer-used objects.
  • works in the background at runtime.

  • Python core time (ptime)

  • is the total time of compile time and runtime.

  • compile time (ctime)

  • is the time when bytecode compiler is compiling Python code into bytecode.

  • runtime (rtime)

  • is the time when VM is running the bytecode compiled by BC.
  • can also be called execution time, running time, etc but I use runtime because it's shorter.

  • pre-Python core time (pptime)

  • is the time before ptime to check Python code with type checkers, linters, etc.
  • can also be called static analysis time but I use pre-Python core time(pptime) because the abbreviations pptime and ptime are a good combination.