Programmer Maturity and Estimation Skill

How do you measure a programmer maturity?. Recently, I am beginning to think that it is reflected on how they estimate the project and task that they need to do.

Programmer that only work on small number of code and problem tend to highly overestimate or underestimate the complexity of a project/task. So, mature programmer is not (just) someone who could code, and estimate, very good and precise in well-known problem using language that he knows well. A mature programmer would also :

• know quite clearly what he need to do/learn/research on matters that he is not used to
  
• how much/how certain/uncertain the time to take to tackle it, substask and trouble that potentially come up
  
• make clearly-thought estimation, and most importantly
  
• not emotionally attached to a problem which means not knowing or estimate something as long/hard/unknown/impossible is nothing to be embarassed/defensive about instead it's for the best if everyone being clear on what can and cannot be done
  

Less mature one would tend to be more "aggresive" and eager to prove himself by estimating too optimistically or underestimating a complexity of certain task (by fear of losing credibility or eagerness to be accepted/approved).

I think it's the same as maturity in life, you are less needing of approval/praise or trying to satisfy/impress anybody too much and more focus on doing what you can do best and keeping your integrity checked.

It does not mean we need to avoid the unknown and avoid adventure, but being mature means being clear of it and not promising something beyond our integrity to accomplish it. Say something is risky when it is and let the stakeholder decide (and share consequences later), say something certain when you have a reference/experience of it and ready to take consequence if you are proven to be wrong (you learn something new anyway).