This ProBuilder code snippet demonstrates how to set an expiration date for an indicator and provide advance warnings to the user. The code is useful for scenarios where an indicator should only be used until a certain date, after which it becomes obsolete or needs renewal.

expirydate = 20180101
advancewarningdate = 20171201
if opendate >= advancewarningdate then
    if not donewarning then
        drawtext("Warning - this indicator will expire in one month",barindex,result[1],SansSerif,Bold,16)coloured(128,0,0)
        donewarning = 1
    endif
endif
if opendate < expirydate then
    result = average[200] //replace with your indicator code
else
    result = undefined
    if not done then
        drawtext("Warning - this indicator has expired",barindex,result[1],SansSerif,Bold,16)coloured(128,0,0)
        done = 1
    endif
endif
return result

This code snippet includes several key programming concepts:

• Conditional Statements: Uses if and endif to control the flow of the program based on the date conditions.
• Variables: Utilizes variables like expirydate, advancewarningdate, donewarning, and done to store dates and state information.
• Text Drawing: Employs drawtext function to display messages directly on the chart, which is useful for alerts.
• Color and Style Formatting: The text is styled and colored to ensure visibility and impact.
• Logical Operators: The not operator is used to check if a warning has already been issued, preventing repeated alerts.

Step-by-step explanation:

• The code first checks if the current date (opendate) is equal to or later than the advancewarningdate. If true, and if no previous warning has been issued (donewarning is false), it displays a warning message about the impending expiration.
• If the current date is still before the expirydate, the indicator calculates and returns its usual result (in this case, a 200-period average).
• If the current date is past the expirydate, the result is set to undefined, and an expiration message is displayed if not already done.

This example is particularly useful for developers looking to add time-sensitive features to their ProBuilder scripts, ensuring users are aware of the validity period of the indicators.