decorators.md

Decorators

Decorators in TechLang provide a way to wrap functions with additional behavior, similar to Python's @decorator syntax.

Defining a Decorator

Use the decorator command to define a decorator:

decorator <name> <before|after|both> do
    # code to run before/after the decorated function
end

Decorator Modes

• before - Code runs before the original function
• after - Code runs after the original function
• both - Code runs both before and after (use markers to separate)

Example

# Define a logging decorator
decorator logger before after do
    print "[LOG] Function starting"
    # original function executes here
    print "[LOG] Function finished"
end

# Define a function
def greet name do
    print "Hello,"
    print name
end

# Apply the decorator
decorate greet logger

# Call the decorated function
call greet "World"
# Output:
# [LOG] Function starting
# Hello,
# World
# [LOG] Function finished

Applying Decorators

Use decorate to apply a decorator to an existing function:

decorate <function_name> <decorator_name>

Multiple Decorators

You can apply multiple decorators to a function:

decorator auth do
    print "Checking authentication..."
end

decorator log do
    print "Logging call..."
end

def api_call do
    print "API response"
end

decorate api_call auth
decorate api_call log

call api_call
# Output:
# Checking authentication...
# Logging call...
# API response

Built-in Decorators

TechLang provides built-in decorators:

@log

Logs function entry and exit with timing:

decorate my_func log

@time

Measures and reports function execution time:

decorate my_func time

Use Cases

• Logging: Add consistent logging to functions
• Timing: Measure function performance
• Validation: Check preconditions before execution
• Caching: Memoize function results
• Authentication: Verify permissions before execution