flytekit.core.condition

Directory

Classes

Methods

Methods

conditional()

def conditional(
    name: str,
) -> ConditionalSection

Use a conditional section to control the flow of a workflow. Conditional sections can only be used inside a workflow context. Outside of a workflow they will raise an Assertion.

The conditional method returns a new conditional section, that allows to create a - ternary operator like if-else clauses. The reason why it is called ternary-like is because, it returns the output of the branch result. So in-effect it is a functional style condition.

Example of a condition usage. Note the nesting and the assignment to a LHS variable

v = (
conditional("fractions")
.if_((my_input > 0.1) & (my_input < 1.0))
.then(
    conditional("inner_fractions")
    .if_(my_input < 0.5)
    .then(double(n=my_input))
    .elif_((my_input > 0.5) & (my_input < 0.7))
    .then(square(n=my_input))
    .else_()
    .fail("Only <0.7 allowed")
)
.elif_((my_input > 1.0) & (my_input < 10.0))
.then(square(n=my_input))
.else_()
.then(double(n=my_input))
)

create_branch_node_promise_var()

def create_branch_node_promise_var(
    node_id: str,
    var: str,
) -> n: The generated unique id of the variable.

Generates a globally (wf-level) unique id for a variable.

When building bindings for the branch node, the inputs to the conditions (e.g. (x==5)) need to have variable names (e.g. x). Because it’s currently infeasible to get the name (e.g. x), we resolve to using the referenced node’s output name (e.g. o0, my_out,… etc.). In order to avoid naming collisions (in cases when, for example, the conditions reference two outputs of two different nodes named the same), we build a variable name composed of the referenced node name + ‘.’ + the referenced output name. Ideally we use something like (https://github.com/pwwang/python-varname) to retrieve the assigned variable name (e.g. x). However, because of https://github.com/pwwang/python-varname/issues/28, this is not currently supported for all AST nodes types.

merge_promises()

def merge_promises(
    args: `*args`,
) -> typing.List[Promise]

to_branch_node()

def to_branch_node(
    name: str,
    cs: ConditionalSection,
) -> Tuple[BranchNode, typing.List[Promise]]

to_case_block()

def to_case_block(
    c: Case,
) -> Tuple[Union[_core_wf.IfBlock], typing.List[Promise]]

to_ifelse_block()

def to_ifelse_block(
    node_id: str,
    cs: ConditionalSection,
) -> Tuple[_core_wf.IfElseBlock, typing.List[Binding]]

transform_to_boolexpr()

def transform_to_boolexpr(
    expr: Union[ComparisonExpression, ConjunctionExpression],
) -> Tuple[_core_cond.BooleanExpression, typing.List[Promise]]

transform_to_comp_expr()

def transform_to_comp_expr(
    expr: ComparisonExpression,
) -> Tuple[_core_cond.ComparisonExpression, typing.List[Promise]]

transform_to_conj_expr()

def transform_to_conj_expr(
    expr: ConjunctionExpression,
) -> Tuple[_core_cond.ConjunctionExpression, typing.List[Promise]]

transform_to_operand()

def transform_to_operand(
    v: Union[Promise, Literal],
) -> Tuple[_core_cond.Operand, Optional[Promise]]

flytekit.core.condition.BranchNode

class BranchNode(
    name: str,
    ifelse_block: _core_wf.IfElseBlock,
)

Properties

flytekit.core.condition.Case

class Case(
    cs: ConditionalSection,
    expr: Optional[Union[ComparisonExpression, ConjunctionExpression]],
    stmt: str,
)

Methods

fail()

def fail(
    err: str,
) -> Promise

then()

def then(
    p: Union[Promise, Tuple[Promise]],
) -> Optional[Union[Condition, Promise, Tuple[Promise], VoidPromise]]

Properties

flytekit.core.condition.Condition

class Condition(
    cs: ConditionalSection,
)

Methods

elif_()

def elif_(
    expr: Union[ComparisonExpression, ConjunctionExpression],
) -> Case

else_()

def else_()

flytekit.core.condition.ConditionalSection

ConditionalSection is used to denote a condition within a Workflow. This default conditional section only works for Compilation mode. It is advised to derive the class and re-implement the start_branch and end_branch methods to override the compilation behavior

Usage:

v =  conditional("fractions").if_((my_input > 0.1) & (my_input < 1.0)).then(...)...

class ConditionalSection(
    name: str,
)

Methods

compute_output_vars()

def compute_output_vars()

Computes and returns the minimum set of outputs for this conditional block, based on all the cases that have been registered

end_branch()

def end_branch()

This should be invoked after every branch has been visited. In case this is not local workflow execution then, we should check if this is the last case. If so then return the promise, else return the condition

if_()

def if_(
    expr: Union[ComparisonExpression, ConjunctionExpression],
) -> Case

start_branch()

def start_branch(
    c: Case,
    last_case: bool,
) -> Case

At the start of an execution of every branch this method should be called.

Properties

flytekit.core.condition.LocalExecutedConditionalSection

ConditionalSection is used to denote a condition within a Workflow. This default conditional section only works for Compilation mode. It is advised to derive the class and re-implement the start_branch and end_branch methods to override the compilation behavior

Usage:

v =  conditional("fractions").if_((my_input > 0.1) & (my_input < 1.0)).then(...)...

class LocalExecutedConditionalSection(
    name: str,
)

Methods

compute_output_vars()

def compute_output_vars()

Computes and returns the minimum set of outputs for this conditional block, based on all the cases that have been registered

end_branch()

def end_branch()

This should be invoked after every branch has been visited In case of Local workflow execution, we should first mark the branch as complete, then Then we first check for if this is the last case, In case this is the last case, we return the output from the selected case - A case should always be selected (see start_branch) If this is not the last case, we should return the condition so that further chaining can be done

if_()

def if_(
    expr: Union[ComparisonExpression, ConjunctionExpression],
) -> Case

start_branch()

def start_branch(
    c: Case,
    last_case: bool,
) -> Case

At the start of an execution of every branch this method should be called.

Properties

flytekit.core.condition.SkippedConditionalSection

This ConditionalSection is used for nested conditionals, when the branch has been evaluated to false. This ensures that the branch is not evaluated and thus the local tasks are not executed.

class SkippedConditionalSection(
    name: str,
)

Methods

compute_output_vars()

def compute_output_vars()

Computes and returns the minimum set of outputs for this conditional block, based on all the cases that have been registered

end_branch()

def end_branch()

This should be invoked after every branch has been visited

if_()

def if_(
    expr: Union[ComparisonExpression, ConjunctionExpression],
) -> Case

start_branch()

def start_branch(
    c: Case,
    last_case: bool,
) -> Case

At the start of an execution of every branch this method should be called.

Properties