DevelopmentStyle

Python Coding Style

Type Prefixing

We prefix all variable, function and method names with a lowercase letter that indicates the type; it helps you anticipate what type a quantity is, and to make explicit type conversions. This is not a rigid requirement, but it helps cut down on a very common type of mistake, pun intended.

If the type changes, assign it to a new name with the initial letter changed. In Python, this scheme has the added advantage of avoiding any naming conflict with built-ins, or most Python standard library modules.

Choose the initial letter from the following list:

	Prefix Letter		Variable Type
	a		numpy array
	b		boolean
	c		complex
	d		alist or dictionary
	e		error string return value, empty for success
	f		double
	g		generic - unknown or mutable
	h		hypertext - HTML/XML entity encoded string
	i		integer
	l		list set or tuple
	o		instance or pointer to a class
	r		pandas series
	m		pandas dataframe
	p		pandas panel
	s		ASCII string
	t		date/time value
	u		Unicode string
	v		void - return value not to be used
	z		non-empty string return - empty is a failure

We use a similar prefix notation in theMQL4 library code: https://github.com/OpenTrading/OTMql4Py/wiki/DevelopmentStyle

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