Module 2

The HtDF recipe consists of the following steps:

Step 1: Write the stub, including signature and purpose

Step 2: Define examples

Step 3: Write the template

Step 4: Code the function body

Step 5: Test and debug until correct

Step 1: Write the stub, including signature and purpose

@typecheck
def double(n: float) -> float: #signature
    """
    returns n doubled 
    """#purpose(属于stub)
    
    return 0      #stub[取决于output类型]

Stub作用：The stub serves as a scaffolding to make it possible to run the examples even before the function design is complete.

Step 2: Define examples

from cs103 import *

@typecheck
def double(n: float) -> float:
    """
    returns n doubled
    """
    
    return 0      #stub
________________________________下面的是examples
# Begin testing
start_testing()

expect(double(0), 2 * 0)
expect(double(-2.1), 2 * -2.1)
expect(double(10.11), 2 * 10.11)

# Show testing summary
summary()

Tips:
1.Examples 不光是 HtDD中的L10=12.3 这种的examples，在HtDF中就是这种在testing中的Examples
同时具有test 和eaxmples的作用

2.每个情况都要有一个 examples，不要疏漏

Step 3: Write the template

包含所有的自变量，ex：例子中的 n

from cs103 import *

@typecheck
def double(n: float) -> float:
    """
    returns n doubled
    """
    
    # return 0      #stub
________________________________下面的是template
    return ...(n)   #template
________________________________下面的是examples
# Begin testing
start_testing()

expect(double(0), 0)
expect(double(-2.1), 2 * -2.1)
expect(double(10.11), 2 * 10.11)

# Show testing summary
summary()

Step 4: Code the function body

@typecheck
def double(n: float) -> float:
    """
    returns n doubled
    """
    
    # return 0      #stub
    # return ...(n) #template
    return 2*n

给template前加“#”
同时给方程body（灵魂运算)

Step 5: Test and debug until correct