tjaved573

||=

a || = b

is a conditional operator. Assign b to a if a is uninitialized.

tjaved573

Keyboard shortcuts ———————————————

Show suggestion - ctrl + space

Shifting between terminal and window: Terminal ctrl ` , Window ctrl 1

Open keyboard shortcuts : cmd K + cmd S

tjaved573

# Ruby Yield Statement


# Yield statement is used for a method that takes in a block and needs to invoke the code block.
# In this e.g, name() method takes in a block defined in line #10. 
# In the method definition, wherever 'yield' keyword comes up, the code block is rendered.

def name
  puts "A yield will be called with id of 12"
  yield 12

tjaved573

to list all installed packages installed

pip3 list

to create a virtual environment

virtualenv test_env_1

to specify a version as well, run:

virtualenv -p /usr/local/bin py_env_3.8

to active a virtual environment, use

source test_env_1/bin/activate

tjaved573

# with this syntax, the order of parameters does not matter
# have to use same name for parameters when passing arguments

#! required and optional arguments are ordered
#! order of passing parameters
  #! required => optional => variable => keyword

#! keyword arguments => for more clarity, and removing the need for arguments to be ordered
def method_1(m1:, m2:, m3:)

tjaved573

# single splat operator converts all arguments into an array.
# double splat operator converts all arguments into a hash

# order of arguments:
  #// required -> optional -> variable -> keyword (use hash syntax)

def dubSplat (*c, **d)
  p c
  p d
end

tjaved573

#// RAILS ASSOCIATIONS

class Author
  has_one :book   
    # indicates that one other model has a reference to this model.
    # Rails assumes that Books.author_id is a foreign key to Author.id in this table.
end

class Book < AR
  belongs_to :author