EH.. you dont really have to code from scratch the whole trading program. There already exists program like metastock, metatrader, ninjatrader which has all the things you need to backtest your trading rules. You just need to learn very simple script syntax (if you are comp science..should be no problem) and codify your rules.
I Think wahkao meant using those programs to backtest.
that will mean that the method is a mechanical method already, because u can only backtest mechanical methods accurately, but this method is not a mechanical method its a discretionary method, 2 same price action, i might take different actions if the feel is different, and also, i do take into account news and sentiment say gdp, unemployment or interest rate numbers and see if the volatility fits the expected move or not, say if we get a up stick which is only a little bit stronger than the other candle sticks before that, in a bearish d1 trend, while the news is producing bullish numbers, it tells me the market is still weak, and can be expected to break lower, and i fade the news move when it shows me a turning point. price action has to be seen relative to the other bars preceeding it with a general feel to it, its not something computers are good, because humans are just better at pattern recognition, even pinbars have their differences, some pinbars have small tails, and i just let it skip by, other pinbars with very long tails then i fade it if there is no news near it or if we are at very near some speculated stop levels, pinbars forming in slow markets are not good to take because it may very well be noise, while pinbars in violent markets are extremely informative, and good to trade, these are things which i won't say is impossible to code, but is just very difficult and cumbersome and needs alot of finetuning to express in code, i might as well trade manually, plus i love trading also so its a fun thing for me to do, as there is no incentive for me to code an algo as its taking the fun out of trading for me.
i have coded EA on metatrader 4 also, anything slower than price action is not suitable for intra-day trading, which is my scope for analysis, and my sole focus, however for indicators if u want to use them, should be on higher timeframes of at least daily backed by macro factors, or use the hourly charts, but with say 5*24 periodicity to peg it to the weekly.
also, there are somethings, which as a trader u can pick out, like background buying or selling, which are hard to code algos for. trading is just like playing dota 2, there is always the uncertainty there, so bots are easy to game and manipulate as well. if u want to see how stop hunting can be done, i can show u 1 example if i were a market maker how i will do it.
say we are in a slow ranging market before the opening hours of frankfurt, sgt 1.30pm, and the overall daily trend is bearish. however, since im a market maker and i am interested in getting more shorts open to fill large orders coming in for the day so i don't have to be net long which is dangerous for me to be against the trend. there are stops above the current range, so i want to hunt them and establish my position, first, i put limit longs below the market, then i hit the bid to attract in indicator guys to fill my longs, then i see them also putting more stoplosses up there, so i establish sell limits above, and then i sell massively into the stoplosses and stop orders above, and become net short, and simply wait for the large guys to come in, and i can just take profit from the large specs by quoting them a price which is better than my net short position price, and i can then ride a small short position into profits while being squared, all the time collecting scalp money or spreads. this is 1 way to do stop hunting from a flat position, and make money to the up side and down side.
this is a 1 off scenario, and there are many more variations of how market makers trade, and by understanding how the various participants are acting, its possible to deduce to a high degree of accuracy what the next move is, because they already showed their hand, if they want to do something funny it will be at their own detriment lest they invite other sharks to go after them, all u need to do is go with the price action.
with all that being said, i don't think scripts are sophisticated enough to model for these kind of stuff, essentially ur creating a very sophisticated AI capable of studying human crowd behavior and predicting to a high degree of accuracy what the next most probable course the market might take, it will have to be a standalone program coded in c for speed.