How can I add a required step before a built-in function runs after calling it?

For example, sometimes in a stupor I type in 'clear' and press enter when I mean to type in 'clear x' and press enter. Is there anyway I can require an extra keyboard input after using 'clear' to prevent accidentally clearing all variables? I would like to be prompted by 'Press 'y' if you want to clear all variables.' Is this possible?

Answer 1

[the cyclist]

I think the simplest way to do this would be to make a function called myclear, which behaves the way you want. For example, it could first check whether you called it with arguments, check with you, then call the MATLAB clear command.

You could use the nice keep function from the File Exchange as a model for how to construct the exact behavior you want.

[Image Analyst]

No need for the File Exchange keep function with recent versions of MATLAB:

clearvars variables -except keepVariables 

removes the variables specified by variables, and does not 
remove the variables specified by keepVariables. This syntax 
allows you to use a combination of variable names, wild card 
characters, or regular expressions to specify variables to remove
or keep.

[Kelly]

Thanks for the great suggestion. I wrote this function. I'm sure it will save me in the future.

 function [cl] = myclear
 clc
 prompt = 'Select from the following:\n1=>Clear all variables.\n2=>Clear all variables except those specified.\n3=>Clear only specified variables.\nPress any other key to exit.\n\nYour Choice:';
 str = input(prompt,'s');
 clc
  if isempty(str) || (str ~= '1' && str ~= '2' && str ~= '3')
      disp('Variables will not be cleared.')
  elseif str == '1'
      evalin('caller','clear') 
  elseif str == '2'
      prompt = 'Enter variable names to keep separated by spaces.\n\nVariable Names:';
      str = input(prompt,'s');
      evalin('caller',['clearvars -except ' str])
   elseif str == '3'
      prompt = 'Enter variable names to clear separated by spaces.\n\nVariable Names:';
      str = input(prompt,'s');
      evalin('caller',['clearvars ' str])
  end