Conversion to Julia

Conversion Rules

The following table specifies the conversion rules used whenever converting a Python object to a Julia object. If the initial Python type matches the "From" column and the desired type T intersects with the "To" column, then that conversion is attempted. Conversions are tried in priority order, then in specificity order.

From Julia, one can convert Python objects to a desired type using pyconvert(T, x) for example.

From Python, the arguments to a Julia function will be converted according to these rules with T=Any.

From	To
Top priority (wrapped values).
`juliacall.AnyValue`	`Any`
Very high priority (arrays).
Objects satisfying the buffer or array interface (inc. `bytes`, `bytearray`, `array.array`, `numpy.ndarray`)	`PyArray`
High priority (canonical conversions).
`None`	`Nothing`
`bool`	`Bool`
`numbers.Integral` (inc. `int`)	`Integer` (prefers `Int`, or `BigInt` on overflow)
`float`	`Float64`
`complex`	`Complex{Float64}`
`range`	`StepRange`
`str`	`String`
`tuple`	`Tuple`
`collections.abc.Mapping` (inc. `dict`)	`PyDict`
`collections.abc.Sequence` (inc. `list`)	`PyList`
`collections.abc.Set` (inc. `set`, `frozenset`)	`PySet`
`io.IOBase` (includes open files)	`PyIO`
`BaseException`	`PyException`
`datetime.date`/`datetime.time`/`datetime.datetime`	`Date`/`Time`/`DateTime`
`datetime.timedelta`	`Microsecond` (or `Millisecond` or `Second` on overflow)
`numpy.intXX`/`numpy.uintXX`/`numpy.floatXX`	`IntXX`/`UIntXX`/`FloatXX`
Standard priority (other reasonable conversions).
`None`	`Missing`
`bytes`	`Vector{UInt8}`, `Vector{Int8}`, `String`
`str`	`String`, `Symbol`, `Char`, `Vector{UInt8}`, `Vector{Int8}`
`range`	`UnitRange`
`collections.abc.Mapping`	`Dict`
`collections.abc.Iterable`	`Vector`, `Set`, `Tuple`, `NamedTuple`, `Pair`
`datetime.timedelta`	`Dates.CompoundPeriod`
`numbers.Integral`	`Integer`, `Rational`, `Real`, `Number`
`numbers.Real`	`AbstractFloat`, `Number`, `Missing`/`Nothing` (if NaN)
`numbers.Complex`	`Complex`, `Number`
`ctypes.c_int` and other integers	`Integer`, `Rational`, `Real`, `Number`
`ctypes.c_float`/`ctypes.c_double`	`Cfloat`/`Cdouble`, `AbstractFloat`, `Real`, `Number`
`ctypes.c_voidp`	`Ptr{Cvoid}`, `Ptr`
`ctypes.c_char_p`	`Cstring`, `Ptr{Cchar}`, `Ptr`
`ctypes.c_wchar_p`	`Cwstring`, `Ptr{Cwchar}`, `Ptr`
`numpy.intXX`/`numpy.uintXX`/`numpy.floatXX`	`Integer`, `Rational`, `Real`, `Number`
Objects satisfying the buffer or array interface	`Array`, `AbstractArray`
Low priority (fallback to `Py`).
Anything	`Py`
Bottom priority (must be explicitly specified by excluding `Py`).
Objects satisfying the buffer interface	`PyBuffer`
Anything	`PyRef`

See here for an explanation of the Py* wrapper types (PyList, PyIO, etc).

Custom rules

To add a custom conversion rule, you must define a function to do the conversion and call pyconvert_add_rule to register it.

You must not do this while precompiling, so these calls will normally be in the __init__ function of your module.

Missing docstring.

Missing docstring for PythonCall.pyconvert_add_rule. Check Documenter's build log for details.