Program Comprehension:Past, Present, and Future

Janet Siegmund

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Program Comprehension in the Past

Programming in the past?

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Higher-Level Programming Languages

Soloway & Ehrlich, 1984: Empirical Studies of Programming Knowledge

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Measuring Program Comprehension

For… that‘s a loop… i = 1..2…3

?

Fill in the blankMemorization

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Return Value of b

It should compute the median

Case for the odd array

That‘s the list of numbers…b should be 4.5

Case for the even array

public static void main(String [] args) {int [] data = {1, 2, 4, 5, 6, 10};computeMedian(data);

}

public int computeMedian(int[] data) { int[] data = data; sort(data); float b;

if (data.length % 2 == 1) b = data[data.length / 2]; else b = ((float) data[data.length / 2 - 1] +

(float) data[data.length / 2]) / 2;

return (b);}

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Bottom-up comprehensionpublic static void main(String [] args) {

int [] data = {1, 2, 4, 5, 6, 10}; (data);

}

public int (int[] data) { int[] data = data; sort(data); float b;

if (data.length % 2 == 1) b = data[data.length / 2]; else b = ((float) data[data.length / 2 - 1] +

(float) data[data.length / 2]) / 2;

return (b);}

Weird variable naming

Check for odd array length…does not apply here

Even array… get entries at half the length… 4 and 5… sum and divde by 2… 4.5

it‘s the median

elephant

elephant

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• How does this help us tounderstand theprogrammer of today?

• A little:– Useful variable names– Code layout– Tool support

public int enterprise (int[] kirk) { int[] data = kirk; sort(data); float picard; if (data.length % 2 == 1) picard = data[data.length / 2]; else picard = ((float) data[data.length / 2 - 1] +

(float) data[data.length / 2]) / 2;

return (picard);}

Present

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Why Did Research onProgram Comprehension Stop?

What is more productive to use, a statically or dynamically typed language?

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In the wild (realistic) In the lab (controlled)

Maximizeinternal validity

Reliably explains the causes of effects

Hard to generalize

Maximizeexternal validityReveals generally occurring effects

Causes of effects unclear A fundamentaltradeoff!

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Neuro-Imaging MethodsElectroencephalography (EEG)

Higher cognitive load during programming task is reflected in the EEG signal

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Functional Magnetic Resonance Imaging

Mirror

Screen

Head coil

MRI scanner

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public static void main(String[] args) { int[] array = {1, 2, 4, 5, 6, 10}; sort(array); float b;

if (array.length % 2 == 1) b = array[array.length / 2]; else b = ((float)array[array.length / 2 - 1]

+ (float)array[array.length / 2]) / 2;

System.out.println(b);}

public static void main(String[] args) { int[] array = {1, 6, 4};

for (int i = 0; i <= array.length / 2 - 1; i++){ int tmp = array[array.length - i - 1]; array[array.length - i - 1] = array[i]; array[i] = tmp; }

for (int i = 0; i <= array.length - 1; i++) { System.out.println(array[i]); }}

public static void main(String[] args) { String word = "Hello"; String result = new String();

for (int j = word.length() - 1; j >= 0; j--) result = result + word.charAt(j);

System.out.println(result);}

Source-Code Snippets

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BA21BA47Language processing:• Natural and artifical• Semantic processing at word level• Combinatorial aspects

VXVS

VXXXS

Adhering to grammar?

TPTXVS

TPTPS

Results

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BA21

Raven‘s Progressive Matrices

Problem solvingDivided attentionSilent word readingWorking memory

Results

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Concentration : The Default Network

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ResultPosterior cingulate cortex (BA31post)

Posterior cingulate cortex (BA31ant)

Prefrontal midline area (BA32)

Neuro-imaging methods provide interesting new

insights into developer‘s heads

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Perspective: Teaching

Object-oriented programming?

Functional programming?

How should we teach beginning programmers?Language Skills?

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Future

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